My 2 cents: he IS an odd duck. He's very arms-wide-open for certain people at certain times, but other times he's really distant and weird. I think he's socially awkward and doesn't know how to deal with the attention that he gets (even though he pretends to want it). I've seen it a lot with comedians, too. They interact and engage with people online comfortably, but face-to-face they crumble and can be awkward and rude.
But like you said, I think WE are the rare exception. We just want to acknowledge that we like someone and appreciate what they do, when everyone else wants something (photos, autographs, a moment of recognition). John Barrowman said some really nice things on the Nerdist show about how too many people get shy or rebuff their fans and he hates it. He said that he owes his career and success to the fans, so he will always spend the time to engage with fans who come up to him, because he is grateful. The other guys were like "um, yeah" because they don't have the same attitude about it.
There's a great documentary about Conan O'Brien and he talks about this, where he tries to make time for as many people as he can after a show. So he'll say from the start that he only has 15 minutes or whatever, and he'll spend that 15 minutes taking pictures, signing autographs, whatever but after that he has to leave and there's always SOMEONE who didn't get what they wanted and calls him an asshole. And how much that hurts him -- it's not his fault that he can't spend hours and hours with every fan, every day. It brought him to tears.