Ignore OR Confront?

I've mentioned before how I introduced myself to neighbours and that when I saw the man of the house out on the street, he blatantly avoided me for seemingly no reason at all. I have felt compelled to confront him about it in the friendliest possible way, but I also feel it'd be best to just move on and not rattle any potential hornets nests. I think it'd be a good display of self-respect to look for answers for this behaviour, but on the other hand I think leaving them alone and moving on could be the ideal solution.

What do you think I should do?

leave him alone you dont know whats on his mind

They don't owe you anything.

I know they don't owe me anything, but there's nothing wrong in being upfront about it.

There is, you have no place confronting them going about their day just because they don't want to interact.

Just ignore him.

He clearly doesn't want to interact and that's his choice to make.
Asking him the reason why or getting accusatory won't change his mind, it will just get him very annoyed and earn you the reputation of an overbearing nuisance of a neighbour.