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

Punish in private. However, the Military I was in, therr was no chance to explain yourself. The order is as follows, soldier is given an order or directive and then they move out. Ask questions later. But, if they act that way then it's paperwork. Nothing beats a papertrail.

What is a Senior E-5?, that must be a National Guard/Reserves classification or is it like E-5 Promoteable maybe

Retired. But, have been on "both sides" of this situation. When I was the lowly E-nothing, I mouthed off in front of the boss, in front of everybody. Was physically dragged outside, thrown against the wall, yelled at, and learned a valuable lesson. I was NOT the lead dog of the pack. Fast forward to when I was the shop boss. They adapted to my style...and if a task wasn't done by the COB day...everyone stayed back. They soon learned to work as a team instead of individuals.

Someone just filled the open slot for cleaning the latrine, until I make CSM.

Insubordination in front of your troops by a lower enlisted private is a death wish and a sure fire way to end your short military career. Everyone in my formation knows that details are handed out fairly and justly and insubordination will swiftly be delt with with. If he wants to be a stud in front of everyone in MY formation, he will quickly find out who is in charge and so will the rest of the platoon!

I would make him and his team leader stand fast while the rest of the platoon went on their way to accomplish the daily duties given. There will be counseling and there will most definitely be corrective training. He might be able to get away with that crap in another platoon, but not mine.

He doesn't attend Berkeley and he doesn't have a safe place here to spout off at the mouth. The only safe places here are behind the rear sight posts of your weapon! And there is no place for insubordination especially when lives may be on the line at some point.

I was a fresh PO3 in the USN and was attached to FMTB West (Field Medical Training Batallion). It is essentially a C-school which allows Navy Corpsmen to operate with the Marine Corps. Unless you're willing to fuck someone up, you're going to allow them to undermine your authority which will in turn make you question yourself which will in turn make your infrastructure of rank and respect dissolve. It is important to lead by example and to understand that even though you're a particular rank, you're still learning too. I had a reservist E-2 who was significantly older than me. He was giving one of my POs a problem. I locked him up right there: "I don't give a fuck if you are 40 years old. You have not earned the title that I have in time in service OR passed an advancement exam. Rank is the only barometer and you will listen or there will be fucking problems, do you understand? Do you like being talked to like this by someone younger than you? Either contribute or get in line.

I give the job to someone else and he's cleaning toilets for a month and if they are not clean his shipmates should see to his attitude adjustment. They are the one's using the filthy bathroom.

As an ANC, I'd have them get a brain scan to see if there was anything in there. After receiving a negative, I'd have them discharged for lack of being an intact human...... :-)

Half right face. Commence to smoke ALL of them then invite ALL PLT NCO's to BBQ.

You put your foot up his rear end & tell him he better unscrew himself.