I really think that he is/was shocked that someone actually retaliated for the shit that he does/did. He seems to have to attitude that he thought he could get away with it because people don't fight in football and there's an unspoken thing of not hitting someone when their helmet comes off. He fails to realize that this isn't pee-wee football and you're dealing with a grown man. The grown men I know wouldn't stand for that kind of shit...period.
I agree. I don't think he thought he was going to get the beat down. I believe he thought it would be over once the helmets were off. It reminded of the scene in Dazed and Confused when the dorky dude shoved the guy at the party thinking it would be broken up before any punches were thrown. Wrong!