"Pushing guys"? He stopped the guy from running into him.
Then he went to walk away.
The guy started talking shit (we all assume since we cannot hear).
So he turns and looks at him.
The guy then jumps as Schilling.
So Schilling hits him before he gets hit.
Being a fighter does not mean you are not allowed to defend yourself. The other dude thought he was tough, he learned that isn't that tough... or smart.
Most real tough guys don't act like that? Like what? Schilling did nothing and instigated nothing. The dude bumped into him, which didn't matter, then talked shit, then jumped at him as if he was going to hit him. Schilling reacted like someone that didn't want to get hit by a total stranger for no reason. It isn't like he jumped on the dude after he fell and kept hitting him or went overboard in any way. He reacted to a guy potentially trying to hit him, then exited the situation once he saw there was no longer a threat.
Lesson? Don't do what that dumbass that got knocked out did.