I would also suggest having a conference. From what I know of most undergraduate physical education programs, students (who later become those PE teachers) receive very little information on adaptive PE. Unless a PE teacher has been specifically instructed in adaptive PE, they're going to have some difficulties with really understanding how best to instruct.
That being said, I've only seen 3 states. Undergraduate programs differ dramatically by school and state. If I were you, I'd double check (as tactfully as possible) on how much training this individual has in adaptive PE. Perhaps come at it from the perspective of his philosophy towards adaptive PE or his/her overall goals for your child.
As difficult as it may be to remain objective (particularly in the face of having an emotional attachment to your child), I would strongly suggest trying to keep it on a business/professional level. I would also suggest that you have him try to track what is happening prior to the behaviors (antecendents), the actual behaviors occuring, and the outcomes of those behaviors (both his and the child's actions). There may be more than meets the eye that's encouraging his or your child's behaviors.
Sorry to sound so medical about the whole thing. I certainly don't want to negate your feelings, your child's feelings, or that of the teacher. However, to get to the bottom of things, I've just found it's best to try to detail out the actual behaviors while trying to maintain a distance. Hopefully that makes sense.