When I worked at a real "progressive" place, I would follow everyone's lead and use s/he if gender was unknown. I still inadvertently use "youse" for the plural you. That started out as a joke, being fum Bvooklyn, myself. One of the Bibles I used as a kid used a capitalized "You" for the plural. Confused me no end until I finally got a rush of brains to the head and figured it out.
Anyhow, my point remains unchallenged: that language is a flexible, growing thing, and as new usages occur "on the street," grammarians follow along with new hypothetical constructs to 'splain 'em, and set those up as "rules." And then they are confounded when the usages change once again.
After all, analogously, the lexicographers did not invent the word "transistor." Bell Labs did, and the dictionarians had to follow up with a new entry in their next edition. So wooncha know it, soon the word "transistor" became synonymous with small pocket radios, for those old enough to recall that. Whoops! Back to the typesetter's bench.
Further examples abound.
Hey, "wooncha." I like it. I think I'll kepe it.
Terry, 230RN