Sometimes I think it's best not to look at buyer's feedback after the sale, but I do check before taking a best offer.
Ugh! Best of luck with this peach. If you do end up with bad feedback, though, I would definitely call eBay. This person certainly has a history.
I never check feedback for a best offer. I'm glad I don't. LOL This guy would end up on my blocked list. Geez!