Depends on the interfering behaviors. Just how bad is it? Are they expecting more because he's gifted? Does he have impulse control issues-- if so telling a child not to do it is not likely to improve, but changing some other factors can be much more effective. Like if the teacher gives everyone a pencil before giving directions, some kids might not be able to pay attention. Teachers learn not to give the materials until the children are ready to start.
So you need to get a better understanding before passing judgment on the kid or the teachers/program. And that involves working more closely, on the same team as the teachers, if possible without harming your son. But if it's emotionally harming him, then need to intervene. You know your child and that he is fine in the summer, so need to look more. It may just be as simple as giving him engaging work and cutting back on the nonengaging work.
