Are they trying to resolve the anger issues or just trying to control him as he goes through the system? I had some anger issues when younger and thank God I got help and got those issues under control before going to jail or somebody hurting me badly. Sooner or later anger will get a person into some trouble they can't get out of. Not knowing what preceded the teacher restraining him, it is hard to tell if it was necessary or not. My son would get angry and at one point, I was away from home, he was going off the deep end, self-harm was a real possibility. My wife called the police at my request, he spent the night in jail. That was the beginning of healing for him. He was assigned a counselor, he talked about his problems until they were sorted out.