The thing about Autism is, it's a spectrum. So, what 10 kids may or may not do, doesn't mean the other 1 or 2 kids may or may not do the same.
There is no question, anywhere, that D is on the spectrum. He is FIRMLY Pervasive Developmental Disorder (PDD)-not otherwise specified, questions of Aspergers - doesn't really matter. I can tell you that, for my son, ANY type of social group (we tried karate, for example) was a nightmare for him. Not only did the anxiety overtake him, but being around others, interacting with peers, has ALWAYS been a challenge. At 12, he still does not have one friend. He has aquaintances, peers he may tolerate for brief moments, but they all cause an issue one way or the other. It's either because he doesn't get sarcasm with them, or he takes things personally, cannot read body language, etc. He has the social interaction of a 4 year old. Because, that is what Autism is. It's developmental delays.
When he was in 2nd and 3rd grade he was always out at recess alone, by a tree, singing somewhere. in my opinion, if a child is normally social, that would really rule out Autism Spectrum Disorders (ASD). But, I'm not a doctor and I think you should really see a neuropsychologist with her.