GM is dumb. He knows somethings up and the kid is showing good will and results torwards them. He should have kept all that information to himself and offer support, on top of making special exceptions to him to make sure word about it wouldnt spread. In due time MC could trust him enough to tell him his secret, but he tried to brute force it and got rejected. He could just not punish him and let it be, but decided to antagonize MC instead.
@WillTell the GM asked about it and he refused to answer. That is going against GM's requests, which is a rule. Its a very vague rule on purpose so the GM always has a way to deal with anyone and still be an official rule; imagine they'd need to write a full bloom 1000 page document of rules to cover barely half of what he can deal with such simple worded rule otherwise. Usually you'd use that for good, but in this case it wasnt, but still a rule.