That's a great story 
There's a cashier at one of our local stores who seems to have high-functioning autism, but is still much lower-functioning than I am. There is definitely something obviously different about him; I don't think he could "pass" for NT for a second. It's possible that he may be slightly intellectually disabled, but he doesn't seem to be.
He never looks anyone in the eye, and moves in a very rhythmic manner when he's scanning and bagging items. He also talks to himself a bit. However, he always makes conversation with the customers, and he does his job just as well as the rest of the cashiers. He's not in the least bit unpleasant.
I can see how some people may avoid him because he's so obviously different, but that's their problem. It's clear to me that he tries his best (which is more than I can say for most people), and I've never seen him cause any problems.