I disagree. He left the gym intent on sending Joe packing. Reason was, he heard Joe is whining that he will go home if he doesn't get a phone call. He went to the house, made solidly clear that he is not getting the phone call. When Joe agreed and backed off, he didnt pursue it further.
Whats not to admire here? He made sure to the other guys in the gym what would happen if you keep whining instead of training, made absolutely sure that Joe would have to tread Serra's path and not his own and then finally let it go and resolved the situation amicably.
He showed excellent leadership there .