If you're making jokes about your hiring practices -- particularly after you just did not hire somebody -- you're setting yourself up for a lawsuit.
By the books: of course you're right.
By reality: I'm walking to coffee with my coworker and saying outside the earshot of anyone else. People tell inappropriate jokes under these circumstances. And often times those jokes are self-deprecating, like "ewww, she went to a state school" (just like I did) or "what kind of nerd wears [same kind of glasses he and I both have]?" They're jokes, they're intended as jokes, and everyone does this.
This topic is a good example. How do we know he was joking? Maybe he was, maybe he wasn't. But somebody could claim he wasn't joking, and maybe even convince a judge or jury.
There's a time and place for everything. Laughing with a close coworker about something you both understand is not meant seriously is a world apart from shouting it from your Facebook timeline. The former is clearly OK, but the latter is an obvious lapse of, well, judgement.