The World Health Organization defined disability in 1976 as,
“an existing difficulty in performing one or more activities which, in accordance with a person’s age, sex, and normative social role, are generally accepted as essential components of daily living, such as self-care, social relations, and economic activity"
I think the key phrase here is 'normative social role'. Given that part of an Asperger's diagnosis is clinically significant social impairment, I suspect that disability is the best word to use here. Asperger's is also linked to higher risk for depression and anxiety, if I am recalling correctly, which is consistent with research findings for physical disability.
I think it's important to keep in mind that disability is not in this context suggesting an inability to function, but rather greater difficulty in doing so that would be normatively expected. These very difficulties constitute many of the topics for discussion on this board, do they not?
Oh, and three cheers for sociology!