One therapist told me that AS kids are at high risk of bullying, because they misinterpret social clues, and because bullies tend to over-act their feelings and emotions while trying to jerk other kids around, which means that they show up as easier to read for socially blind (or short sighted) kids. Which makes them attractive.
My son has an Asperger's diagnosis, as well, and I think this is something for you to look into carefully, as well, particularly because he doesn't seem to recognize actual attempts to be friendly when they happen.
