Maybe things are different in American schools, but in my personal experience kids with actual disabilities are off limits to bullies.
I didn't go to a very nice school, the majority of the pupils there were massive pricks, and dangerous pricks too (it was a school on the edge of a UVF controlled council estate, just to give you an idea of the kind of place I'm talking about). But there was a girl there with down syndrome and you DID NOT fuck with her. Even the biggest assholes in the school left her alone - and I'm talking about the sort of teenagers who were members of the junior divisions of paramilitary orgnaisations and who would put somebody in hospital for being Catholic. I even witnessed some of them defending her once against someone who made fun of her behind her back.
Don't get me wrong, it's still awesome, I'm just not particularly suprised. Athough the escorting her everywhere is a bit different I have to say.