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

Don't know about today, but the Army I was in, (1969-71), this soldier would likely develop a close, personal relationship with the dumpster as he GI'd it with a toothbrush. Or maybe extended mess hall duty in the grease trap. If that wasn't enough, he might get invited to "laundry detail." He would report to the supply room, where he'd be greeted by several members of the cadre who'd demonstrate the error of his ways. Laundry bags were stacked up against the walls to prevent excess trauma as he collided with said walls. I'm told the Army's mellowed in recent years, but the above always seemed to do the trick back in the day.

I would have a few por-ta John's delivered every weekend and have him gaurd and scrub each and every one of them.

I would give them their first article 15. With that, I would hope the commander we give them extra duty just to remind them.

Death by Magamboo

I had one soldier under me that thought he was hood and could do what he wanted as a fresh E-2. Never had any problems with any other soldiers before or after him. He got smoked the first time. The second time he got a counseling statement with his squad leader. The third he got a field grade Article 15. Reduction in rank to E-1. Restriction to to the baracks for 30 days. 30 days extra duty and two months half pay. He learned real fast that he didn't run things

In front of God and everyone, choke his punk ass out and ask for a volunteer to do the assigned task. Infantry eat their young. You show weakness you get weakness.

It's simple. The conmand is a conmand. You do not have an option. When given an order and a conmand, you follow through with the said order without complaint or insubordination in any way.
As said by someone else, it's seen as a direct reflection of leadership. So the NCO over him will also feel the length of the whip of correction.
If you don't wanna fall in line and follow your order go ahead and prepare to take up residence at fort couch with a promotion to civilian.

There is that old saying Praise in public and punish in private but in some cases you need to make an example and this is one of those cases. Because the E2 is challenging your authority. Inform this shitbird he will complete to jobs that you gave him or your will start the process of getting him the fyck out of your military. You can do hard time or easy time in the military but the military is going to get their time.

Tell him "where the bear shits in the woods!" At th appropriate time, of course!

Article 15 insubordination