Unfortunately people can troll ebay auctions by bidding on items and not paying for them, sellers are unable to leave negative feedback for buyers.
For the seller, I'd hope the buyer follows through but I'll be keeping an eye out to see if this is relisted.
My fear would be the buyer redeeming the private key and refunding through PayPal.
That's also a very valid concern. Selling a slabbed coin could possibly help in that case.