How well did he do in 7th grade math, and were the disciplinary issues a major factor in the grade or evaluation?
From the school’s point of view, it may be that you have been typecast as one of those “pushy parents” trying to overaccelerate their kid compared to the kid’s readiness (including not disrupting the class). Even if this is an unfair assessment, it is probably what you are up against when you find stonewalling from the school.