But you have to be naive as fuck to think that kind of comment would stand once HR/management saw it.
I'm pretty sure HR saw it. And even if they didn't, it's a pretty
dick move to go "oh, btw, you're not hired after all lol" when the person is in the process of moving. At least pull them aside go "yo, your shit isn't accepted here. Delete that or be fired." and wait for them to fuck up somewhere else.
That said, if FyreWulf is right: Into the bushes with this dude, and there's no reason 343 couldn't have found that AFAIK if they're all up in the community.