My autistic son (who is about the same age as yours) has become very good at "masking", which is unfortunate. It has made things harder in many ways, as the school can't understand why he's having problems with school culture (a ridiculous culture to my mind, but that's another discussion).

I think the school my son attends has been a lot more understanding and progressively minded than the school your son attends (or rather attended), based on what you say here. But there are still challenges, and God help anyone who behaved to me the way these teachers have behaved to you.