I have only heard of tenure at the university level here in Canada, no Teacher should be able to treat your son in such a fashion. That being said, even if she has tenure it does not mean that she cannot be reprimanded. Tenure as far as my understanding goes means that she will always have a job with that board, or school, so if there are class cuts, she would be able to stay before a non tenure individual, but again not sure how that works in the States. Obviously, your Principle is just as unprofessional. Now this is only my opinion, but if he were my son, I would have him taken out of the class. The tension that this teacher gives off is probably not good for his own well being, and she could possibly be taking her anger at you on your son. Is he the only one in his class that has Aspbergers, she could possibly be prejudiced, and assume that because he is autistic, he should be at a lower learning level. She obviously needs to be set straight, but I don't think your son should have to deal with this individual on a daily basis. Do you have a parents association, that you could put a petition of sorts out. If other parents are feeling the same way perhaps the lot of you could take it to the superintendent, or board. Not sure how your educational system works.
I really feel for your son, he must be one great kid.
~Tammy