I still wouldn't lock his team. It is only going to make the situation worse. If you lock it and keep his money, he's going to go ballistic, and that is just bad commishing. If you lock it and give his money back, you are going to lose credibility with your league, as I said earlier.
You are stuck with him. Delete his emails and posts, and leave it at that. Ignore him enough, and he will go away.