It's because, even though I'm a cis male that has never been misgendered, I can empathize much better with the pain of a misgendered trans person than with the pain of any person that was treated by as a "they". To be completely honest I can't even understand why someone would be offended by this. So yeah, I prefer to run the risk of offending by using gender neutral language. And this seems to be the consensus among most institutions that are actually thinking about this kind of things.