Even in TV, we're not going to befriend everyone, but since the poster's problem was with someone so near - right across the street - who will probably be seen often, and they were acting so oddly (ie, not just being avoident) for no obvious reason, to me it would be worth it to at least make an effort to try to be neighborly or find out if there is perhaps a misperception or misinterpretation about something, rather than just writing them off based on a possibly mistaken assumption.
Perhaps there was a problem between him and people who lived there before and he was trying to figure out if the poster was someone different - you just never know!
I think it's worth it to make an effort to be on at least cordial terms with nearby neighbors; but then I'm a little bit southern, except that I don't (can't) bake, but would share a beer or glass of wine!