Kids on the autism spectrum just can't connect "normally" and they can make wonderful targets for other kids.
My son with Asperger's was bullied in elementary school, and it was why we chose to move him to an independent (read private) school going into 7th grade. At the time we had no idea he had Asperger's. We just knew he was different from other kids in ways that went beyond the normal charming individuality of all people. At the private school he thrived. He was smart, and smartness was cherished there. He wound up doing Science Bowl and helping his team go to nationals two years running.
I don't think he eve had any experiences as horrifying as what you've described, but if he had he wouldn't have told me about it. I only learned that a classmate tossed his jacket into someone's yard when that someone called me up to inquire if the jacket was his. Luckily there was some kind of ID in it.
Bullying of any kind, no matter how a kid is "different" should absolutely never be tolerated. Generally we don't tolerate bullying in the workforce (although there are many exceptions to that, I know) and we shouldn't tolerate it anywhere.
I myself was never on the receiving end of it, and I don't think I ever did it -- if I did I've forgotten. I do recall in about fifth grade being on a class trip and making sure I sat with the kid who was the class scapegoat, the one who was bullied and made fun of. It wasn't very comfortable doing that, and I don't know what motivated me exactly, other than I knew that the way he was treated wasn't right. I wish I had done that kind of thing more often.