Agreed, you can't be a team leader, or even a good teammate after doing what Green did. And what happened to Poole is not his fault and I'm not saying he should've punched first, either. I'm just saying once he opted to shove him he should've not taken his eyes off him.
To me the unwritten rules of fighting are simple. If you have beef with someone you get in their face and talk . This is the offer phase. Throwing a punch in the offer phase is "cheap" UNTIL someone does a push. You accept the offer by pushing. At that point, it's on, and the punching begins.