Context, people, context.
Perhaps the aspie is irritating as hell, and had a history of stalking or annoying the said NT over a long period of time. Of course, a bit of lenience might be in order, but most aspies don't happen to wear shirts that say 'DON'T ABUSE ME...I'M ON THE DSM-IV.'
If I knew at least one of the people fairly well, I would hear what the NT is saying to the aspie. Maybe he/she is saying what needs to be said. On the other hand, if the NT is truly abusing the aspie and picking on him/her for things that can't be helped, I would have a word with both of them afterwards (but not at the same time.) I would try to give the NT some background information about Aspergers Syndrome and why the aspie's behaviour seemed to be irritating or annoying. I would then tell the aspie a little bit about social etiquette, without sounding patronising or demeaning.
Calling the cops and using physical violence are vast overreactions.
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"Never try to teach a pig to sing. It wastes your time and annoys the pig."