I didn't take the mention of the guy being a Vet as anything more than a deeper respect..... As in, this guy is a Vet, so I don't want to seem overly harsh because I respect him.
Anyway,,
For years I thought nothing of cussing at people or insulting them. I honestly believed it was normal behavior. My wife explained to me that it was not normal behavior and that most people have never seen outbursts of rage or anger. That started a whole world of change in my actions and my view on the world.
Now, if you're thinking that this guy doesn't respect others who he views as weak,,,, I was that way too. In fact I still am to an extent. I think a man should be a man, not a sissy. I think a man should be strong and unflenching not afraid of any challenge or hardship. I can't stand people that seem to be cry babies and cry like a stuck pig when they hit their thumb with a hammer.
I don't know this guy, and you honestly are providing way too little information.
WWJD? He would take control of the situation with meakness and wisdom. You as a councelor of all people should realize that you can't let someone control the group. Better yet, it would be good to get the others involved in the group in the process of evaluating this dudes actions and explain how it makes them feel.