Your son is just 12 years old. Don't think for one minute you are hurting his chances of being all he can be in this game by rushing out and playing on one of these teams. In fact you may be by doing so. What he needs to be doing at this age is learning the game and enjoy playing the game. There will be plenty of time in the future to seek out top tier teams for him to play on. The focus should be on the type of coaching and instruction he is getting with the major focus on enjoying simply competing and playing the game.