I got helped, y'all!
Here's how I did it:
-- Called 3x and spent 3 hours on the phone
-- Sent like 5,000 messages to the awful original case worker
-- Put the whole story on Twitter and had my friends amplify it
-- After a comrade reached out to AirBnB on twitter to ask what the heck was up with this, and why was I being scammed and how was my money being taken away for unsubstantiated invented claims? AirBnB reached out over DM
-- They assigned a new caseworker, who was AWESOME and called me right away
-- Case worker called back and end of day, and said he'd not only found the guest's claims were fishy and insubstantial (she'd sent AirBnB photos of a small stain on my pillow AFTER she'd stripped the pillowcase off; a dead bug near the windowsill; and boxes I'd received in the mail stacked in my living room ... off-limits to guests and clearly says so in the rules, BTW)!, but that the previous caseworker hadn't followed procedure.
-- My $$$ was refunded to me; AND the case is being used to train other caseworkers.
Long story short -- AirBnB does all they can to make sure hosts can never reach people who can actually help us. MAKE A STINK ABOUT IT. Put it on social media. Have your friends reach out. Public shaming seems to be the only thing they listen to.
But if you've had a case opened against you unfairly, you SHOULD seek restitution. In this case, they assigned a new manager.
It sucks, though. I've spent probably +10 hours of totally uncompensated labor dealing with this case and the Guest from Hell. Just to get back the money I was already paid.
Sigh.
Hope this helps someone else!!!