Part of being a leader is stepping up to those situations. You also have to have enforcers( you being the main one). If he can just push your head away there, than you need to address that fact anyway. I actually don't mind goons, or people working what they want while I'm drilling/teaching, if you have the space. But if he in anyway endangers anyone from being able to work or train tomorrow, he's gonna get a serious talk behind the woodshed. If he undermines, I'll stop what I'm doing and ask him to try his theory on me or anyone of my guys. If he's not interested in progressing as a team he can kick rocks, and I'll point him in the direction. Being confrontational is way better than losing a good training partner due to a blown acl.