I disagree. If your son is good enough, any top team will accommodate him. Especially if they are lacking talent in certain positions. Definitely look to attend other tryouts if you are unhappy with your current situation.
Oh I agree. If a kid is a super stud a top team will accommodate him. But in most cases that kids parents have already been in touch with the club. The tryout is a formality, if they even come at all. The B and C team rosters of the bigger clubs are very light.