I think there is a lot of over-interpretation of his. It never seems to happen to me. When you want to be the victim, you might seem to notice it happening. And certainly, there might be some people who don't like foreigners. But as far as I can tell I don't notice it. Perhaps the author has some other features that might make one want to sit beside someone else. The discriminative feature might not him being a foreigner. Furthermore, as a kid I did not like to sit beside foreigners (anyone I did not know) either. I was scared of anyone.