The one thing that jumps out at me is that you say if you say something to him (a friend of yours) that there may be repercussions at work. Either he isn't a friend of yours and you know it but don't want to admit it, you're making excuses not to confront the issue with him, or you're not that good of friends anyway.
I don't know if he's wrong, if you guys are just hating on him, a combination, or something else completely. We've all seen every situation.
Realize he now has added stress, more responsibility, and has to play a different game now. That's just how it is. Is he just being an asshole? Call him out on it. Is he treating you exactly the same as everyone else? Deal with it. You didn't really give examples of how he's treating you like you're stupid.
Maybe he's trying to make sure you have a good understanding of whatever the issue is (doubtful), maybe he's insecure in his ability and he's trying to boost his self confidence. Who knows, and until you address it, it won't change.
Are you a TM or TL? I'm not saying you are doing the following, just saying to make sure you don't. Either way, you should keep your side of the friendship and respect his new role and responsibilities. Don't expect impartial treatment because you're friends. That's not fair to him. If he's just a piece of crap now, then screw him.