Typo noted but the point remains.
As it happens I agree to some extent with both of you. Like Jamestown1630, I have heard, read, and used "they", "their", and "theirs" to indicate single individuals of unknown sex, for roughly seven decades (I'm 72, but I assume I didn't learn correct English for my first few years). But I also agree that as those are used these days for confused individuals, it rankles me no end.