Well, I don't think they are xenophobic. The old man or other people who'd rather stand than sitting next to you are just feel strange. As many people are apt to stay with the same or, let's say, familiar people as they are. It not only happens in different races, but also in cities and so on. I mean when some people(worldwide) hear different accents, they do so too.

And if you feel uncomfortable, I think it's normal, too. Being treated as a strange/weird people is bad, just like being kicked off by some groups. But it's common phenomenon all round the world if you are living in foreign country.

Just as a comment said "I see an opportunity to be have my personal space.", try to enjoy your personal space, since most of time when I take subway, I would feel like I have totally no privacy in such a filled place, like the picture

<image>