How would you react to an E2 who "smart mouths" you in formation?

He or she would receive intensive military retraining

Quite simple. I take the individual to my office along with another senior leader and fill out the appropriate paperwork. We have tools to handle this. We counsel the individual and explain what will happen next. If they are still non compliant, then NJP is applied. When I was much younger I would have flown into a fit of rage and yelled a lot. As I have grown into senior leadership I have learned to first counsel, document , NJP, finally process for discharge. Not every individual is cut out to be in the military and the millennial generation have to be taught what honor and duty mean and they don't respond to "old school" methods.

I would inform the Marine that "a request is nothing but a polite order.Just because I said please doesn't mean it is up for debate." Complete the task, and we will talk afterwards. If the Marine is still feeling froggy, whatever the excuse, he is gonna be jumping!

Remove him from the formation take them to my office and deal with him in private

I would keep that Soldier standing fast and have another NCO present to protect all parties present.........because if the E-2 has the balls to state what they did in the first place, then they probably have the stones to scream abuse and what not.......and explain to them that they were provided a lawful order to execute their duties. Also, I would inform them that if this type of action happens again, then a recommendation for a Company Grade Article 15 will be submitted for disrespect to an NCO, failure to follow a lawful order, and willful dereliction of duty. And of course, I would have this done in a counseling form and also have all that was present that heard the E-2 say this, write up their narrative in a sworn statement.

They would be cutting grass with scissors at the motor pool after work for rest of week.

Immediately pull the soldier out of the formation (having the soldier stand by by while getting the rest of to work) Then issue a counseling statement, getting the Platoon Sgt involved if needed. This would be a ONE TIME ONLY warning. They do it again and I am going to put them in for an Article 15. I have done this a few times. (Usually it only takes one wake up call to get the soldier to wake up and smell the coffee). Most times between me and the Plt Sgt we were able to take care of things.
Every time we brought a soldier up for an Article 15 for this type of infraction, the commander would send it up the line for a field grade Article 15, if for no other reason than to send a message.

I am not talking about the usual moaning and groaning and bitching and whining. I am talking about the egregious stuff. In the Army everybody bitches and whines

When i wars a 18m year old PFC I wanted to know why a Buck Sergeant put me on filling sandbags. detail. He looked at me and said Y is a crooked letter now get up off your ass and move. This was in October 1967. I have no idea what form of motivation is available to Sergeants now. In basic it weas a Drill Sergeant telling you to step into his office for some special counseling.

There are a few things I would know, if I were in this situation. First from the initial or previous counseling either I or my peers completed for this young military member there may be a situation causing this behavior. Second as stated from all leaders above the individual must be addressed immediately or as stated for this individual to remain behind with their direct line supervision so we can discuss in a smaller detail. Third as we progressed up in responsibility as directed line supervisors we were asked to provide personnel for specific duties as we knew our sections daily activities better than our leadership, as it should be. Finally if this individual subordinate would have never had any issue if his/her leadership were complete and consistent in their mission. No situation is ever exactly the same however if R-E-S-P-E-C-T is given then it is also earned. More than not if there is a breakdown in a unit’s discipline then there is an issue with respect. In the end Leaders never quit and Quitters never lead.

I would explain that he will follow any orders hes given then keep an eye on him.