There's a really good, clearly defined metric for this kind of thing: does what he said effect, in any way, his ability to perform his duties? No? Then leave his job out of it. This is the same kind of irrational bullshit we see when a politician is caught in an extramarital affair or we find out a teacher used to act (very, very poorly) in porn. What they do in their personal time is just that, personal. You can judge them as human beings, you can gnash your teeth and whine about it, but if their job isn't to be faithful, it's irrelevant. It's as simple as that.
People who call for terminations like this have the minds of petulant children. I'm a realist, I understand the importance of public perception, but I also understand that kowtowing to willing participants with delicate sensibilities is tantamount to negotiating with terrorists. Actually, it's worse than that. They're wrong, they're putting themselves in the position to be offended, then, instead of excusing themselves from the situation when they are, they try to force everyone else to adhere to their world view. Which is fine, the boundary conditions allow for that, but they also allow for us to tell them to go screw, among other things.
I don't think they've thought this through all the way, either. Do they want the person to just kill themselves? If not, how are they going to provide for themselves after they're fired? Are the people calling for their termination going to foot the money for living expenses until they find a new position? What positions are they fit to fill, anyway? If they're fired for saying something unrelated to their current job, how are they not unfit for other equally unrelated positions? Do we have some arbitrary distinctions to determine these new qualifications? I'd like to see how those were framed if we do. Like, can the professor become a mechanic? Can the porn teacher train horses? Can John Edwards collect shopping carts outside of Wal-Mart?