What's your personal space? It varies based on where you were born and where you grew up. Invading someone's personal space is perceived as aggressive and noisome and perhaps even threatening, which makes it even worse to assume it must be based on pathology rather than "This person was born in Italy, I'm from Norway" or similar.
Similarly, saying things like "culture doesn't excuse bigotry" is rather pointless, given that culture defines what you consider to be bigotry in the first place. What's perfectly tolerant and open-minded in Russia might be unspeakable in Liberia and vice-versa.
My point is, add a culture out of step with the mainstream notions of propriety to someone with even a relatively mild social dysfunction (not necessarily diagnosable!) and you have a "harasser" in the making, especially if everyone castigates them on the first offense and nobody tells them what they're actually doing wrong.