Brandy,
I know this isn't quite the same, but during our homestudy, I had one of my references call into question my mental stability.
I was so angry and hurt I couldn't see straight. What we ended up doing was an independent psych exam to determine my mental health status in regards to parenting. Actually, we did exactly what the court order birth parents to do when they are trying to get back their kids. It worked and once the cw had something saying I wasn't a mental risk, they were fine to approve me.
Anyway, is it possible that in addition to the letter from the school, you could also get letters from other experts on your son (doctors, therapists, etc). Maybe even ask the cw (or her supervisor if she isn't receptive) what you can do to prove that you son is not violent?
Just a thought.
Blessings,
Jenny