I don’t know what the rules are anymore, with all the sensitivity out there nowadays. But I have always used “their” in the case you describe and nobody has given me any shit for it yet. And, actually, in this quickly changing world in constant flux, I really don’t care enough to keep up anymore with the latest whine. It seems to me that, thanks to the net and the most insane shit going viral on social and vid sites like YouTube, anyone without bona fides can influence the way we express ourselves and this opens us up to egomaniacs without portfolio complete with a personal agenda to influence us simply in order to serve their own shit. Even academics are subject to this. That’s why they have peer groups. My Rule: If I personally don’t agree with them and until an editor demands otherwise, I will continue to express myself as I wish. Also, ad populum arguments don’t work with me. The world is often wrong. Just take a look at it. So, just because a bunch of people feel offended somewhere by something someone says or writes doesn’t mean they are right and it doesn’t mean the rest of the world must drop everything and apologize, then revamp the fucking language. If somebody is insulted by the way I express myself and the words I use, I simply just stop communicating with them if I don’t agree. Fuck ‘em. I put this in the “fuck ‘em” file until otherwise convinced by an authority such as Webster or Oxford.