Let me clarify a little more because there are a lot of variables here
He never says anything to me and doesn't miss my game or practice then it is what it is. I'm not hunting down anybody to see if they are doing another team.
He comes up and asks what I think I'm going to tell him it's a bad idea because the chance of getting hurt isn't worth it. He gets hurt and can't play in the playoff game it hurts the whole team. If he decides to play in the AAU after that then I will absolutely cut him next year.
Playing for two teams at the same time is a recipe for disaster. Chance of overuse injuries go up. Overall chance of injury goes up. At some point there will be a scheduling conflict and you're going to have to choose one which is completely unfair and wrong to do to the other team.
You cannot do whatever you want without some sort of repercussions. Call it a power trip all you want but if you know the deal ahead of time and still make that decision then you have told me everything I need to know.