Of course you're technically right, but the pedantry is out of control. In reality, when speaking English in a professional (and pretty much any other) setting, "sex" means "gender."

I don't think it's worth repeating. I'd say it's repeating this kind of misplaced vernacular revisionism that's making us (in which I controversially refer to the disparate collection of users on HN as a single group) look even more anal and oversensitive than we actually are.