I have conflicting feelings over this. I know that open carry is a thing in Texas, but who crossed the line, if anyone?

I don't open carry or 2 reasons. 1. Your advertising that you are armed. 2. A criminal will target you first and possibly get the jump on you. If a law enforcement officer stops me, I let them know that I'm armed by giving him/her my licenses, insurance and registration whither they ask for it or not. This doesn't apply to long guns.

As a retired law enforcement officer (25 Years Honolulu Police Department, four years as a
Special Deputy US Marshal - District 22, ten years as an investigator, VP and Security Manager of the largest bank in the state of Hawaii ) I have some experience and an opinion about this issue. First; I want to get this out of the way: Opinions and ass-holes - every one has got one. Second; there is a big - huge - difference between some lone guy staggering down the sidewalk or street obviously agitated, carrying a shotgun, rifle or pistol, yelling in a disorderly manner at no one in particular while displaying the most basic precautions of firearm safety and just generally being stupid. Opposed to an organized group of individuals obviously demonstrating in a public place while engaging in a lawful Constitutional and state law recognized activity. Thirdly; The approach demeanor on both sides of the issue dictates a response by law enforcement. Contrary to popular belief, there is an unwritten law of "Contempt of Cop." If the members of this group automatically reacted to the police presence and approach by raising their hands or putting their hands behind their heads, you would almost literally see every danger antenna immediately shoot up from each officer at the scene. I'm here to tell you, when uniformed police officers show up en-mass with the police chief in attendance, what ever happens at the scene is dictated by the chief. The fact that the chief personally tazed one of the group balking at the command to "get on the ground," starts a whole new phase of policing, the rewriting of the probable cause definition and the suspension of all Constitutional Rights and a new one added on. Once the chief gets involved directly in a confrontation, all bets are off that your Constitutional rights are going to be respected - at least until everything gets sorted out at the station, the hospital or the findings of the medical examiner. The matter of "Contempt of Cop" is a real phenomena and is brutally depicted in a video clip involved an arrested in Minneapolis. Fourthly; Even and without equivocation, "even" if an officer commands you to cease what you are doing and commands you to do something - like get on the ground - just do it. I does not work to argue the situation at the moment. You may be embarrassed, you may have your feelings hurt, you may have a good law suit, but being right sometimes winds up being dead, seriously injured, or worse, handcuffed, taken to a station and held pending charges, arrest processing and having to appear in court later to answer for your perceived indiscretion only to have the court dismiss the charges against you. Now that's not the end of it. When you get arrested, the arrest is recorded in the local, state and federal systems. The so-called FBI arrest records are notoriously incomplete or lacking in arrest information. In the past, the record depended on what department decides to send the FBI data card to the Data Center. Now, I believe its automatic and digital depending on the technical advancement of the department. Regardless, the data record only - ONLY - shows an arrest, it does not show dispositions of those arrests. So don't be a martyr and get arrested to prove a point, in the long run, it doesn't help you at all except some faux admiration of your friends for "taking the bullet." So, if you get arrested for a home invasion self defense incident where you had to do a bad guy, you get arrested initially for Murder or Manslaughter (Homicide is only a definition) and your arrest is digitally sent to the FBI Data Center. Five days later, after being indicted by a grand jury, you are released with no charges as the offense was investigated and determined to be excusable in self defense. The FBI record not only shows you have an arrest for Murder or Manslaughter, you were indicted for the crime! Try to get through NICS with that on your record without having to jump through some hoops. Fiftly; (if there is such a word) Even though you've been put through a process, it may take some time and it may take multiple appearances in court, but eventually, the matter will be cleared up and the true facts known. The problem is, its already happened to you and you are the damaged goods. Law enforcement officials have what is called "Qualified Immunity" which gives them some protection of suit if they are found to have performed "under color of law." You on the other hand, have suffered indignity, the loss - probably - of your firearms. The color of law thing has to be determined before you can get any redress for any alleged Constitutional violations committed against you by any law enforcement official. Probably Cause issues are handled in the state courts. Constitutional Rights and violations of Civil Rights issues are handled in the federal courts. BTW: Judges, prosecutors, politicians and pretty much anyone employed by the "government" have some level of this immunity - go figure. And last: Everyone knows now that you and your group has suffered this indignation and blatant violation of the Constitutional Right, reinforced by state law and it makes the sixth page of the local news rag. Then what happens? Well, the matter losses interest by the media, but still generates a lot of opinion by the community. If the issue hits social media and it almost always does, more opinionated, uninformed jack-offs get into the mix. Pretty soon, it gets the attention of an anti-gun group or a bunch of clueless, tennis-shoe wearing alleged moms from a small town in Kansas (nothing against Kansas, folks) to petition their local government and bring about a "cause." This cause is immediately embraced by the local government and elevated to the state. The state now enjoins the cause through their Attorney General and the matter is brought to the state legislators who immediately pass a bunch of laws about background checks. The publicity over the new laws is now encouragement to the Congressional representatives and now it becomes a matter widely discussed by clueless congressmen and women who are scouring the planet looking for victims to hold up to C-SPAN and say, we need to put a stop to this and legislate mandatory universal background checks. So they pass the bill which for some reason gets by the sitting president and becomes law. Then you, the lone martyr of the Texas take-down want to buy a gun to replace the one the police still have from your arrest four years ago and get declined - because you've been arrested in a violent confrontation with police and charged with possession of a firearm (dismissed) resisting arrest (dismissed) and disorderly conduct (dismissed). Now I ask this questions, Who is the winner in this and if there is a winner, what did they win? Just sayin' . . .

Before you travel to specific communities, you need to make sure they don't have local laws outlining open carry. Each level of your community has the right to add to or change State and Federal laws. Federal and State laws allow for a limit to the level local laws can extend to. Cities can institute limitations and non-carry laws. Counties can also have statutes that prevent open carry.
You can open carry in the state, but local areas can have their own limitations.

There will be an investigation. I hate to comment before that proper look at the facts comes in, but, at first glance, it does appear that the officer made a mistake.

The police chief and his henchmen conspired to deprive these people of their constitutional rights. Also his right to open or conceal carry in Texas if you have an LTC. If he did not have an LTC he can't legally open carry or conceal carry on public property. Long guns are excepted. The Police chief and henchmen should all be fired and the city of Olmos Park and these incompetent police officers sued. Another exception to the hand gun law... in Texas anyone who can legally own or possess a handgun or ammunition can LEGALLY keep a handgun in their car as long as it is concealed, and if stopped by the police must reveal the presence of said gun immediately without being asked. It's a fine line.

The time to debate the legalities of a stop and frisk is never in the field. If the police are wrong, that will come out in court. If the suspect had merely complied, he wouldn't have been injured. People need to learn that playing Clarence Darrow in the field can have lethal consequences. Being "dead right" is too great a price to pay to make your point. As a retired Asst. Chief of Police, I never understand the logic of taking a chance of giving up your life just to prove that you think the police officer is wrong. You don't know why he has contacted you, what type of incident he was told this was. In short you have no basis for assessing the correctness of his actions based on what he was told when dispatched. Ask yourself, would you open carry if you were responding to help control a riot in a correctional institution and chance having a prisoner get the gun away from you? Don't judge another until you walk a mile in his shoes. Then, who cares. He's a mile away and you've got his shoes.

The first question I would have is probably a silly one: Did they have a Texas 'Licence to Carry' which I have heard is a requirement to carry either open or concealed in the state?

I’d say there are entirely too many officers from rank and file to chiefs that let that badge go to their heads and think it puts them above the law. I think that every time one of these officers arrests someone on a false charge, knowingly false, then they should have to go do the time their false conviction would have Yielded the person falsely arrested.
That would keep them in check

First I’m wondering if the links were removed or what because there not above.
Second and NOT taking away from what happened but if an LEO tells you to do something you comply and then take it up in Court!!!
NOW the above being stated as a former Leo, what was done to 1SG Grisham, his group and the previous individual was totally uncalled for, unprofessional and illegal!!! I truly hope that the police chief and the other officers were all decertified and fired and if it proves to be criminal they should go to jail!!! And that, just for good measure, a sizable punitive financial figure was awarded to all those affected!
I say decertified because any time a cop is fired, unless they go to jail for it, it isn’t very hard for them to move on to another town, state, etc and pick up a new badge. Most places need officers, especially trained and certified officers so bad they are willing to overlook past bad behavior thinking well they got fired for it once so they won’t do that again! And maybe they won’t, but really what’s stopping them from falling into those bad habits again? Especially if all they got was a slap on the wrist the last time and finally fired! Yes I said finally, I mean it’s not like the military where you can screw up once and be roasted! With civilians it seems to take a lot of repeat offenses before anything is done especially with LEOs! I have some ideas on this but that is a horse of a different color!

We all know how solders are treated off base By local police .This is a problem but most command will take the side of local police and them make that town off limits for a short while .But never holding the locals accountable.Look at fort Brag ,Fayetville nick name was faytname/ FDort Hood off of north post WAS Gaitsville and that was off limits in the 80's .You have the hair cut out of state plate you are a target for money for the fines As the military would not back the solders in a lot of local matters .To open Carrie is just another reason to harass the solder .