A caring uncle who came to his nephew's defense?

You were totally in the right! It makes me sad that we had idiots like that teaching the youth. What your brother was doing is borderline abusive and he was completely out of line. If your nephew cannot physically do something, you would think his father would stand up for him. Your nephew is lucky to have such a caring uncle. Keep in mind that you may be the only person that he can turn to when things go badly. Don't let him down! :)