If I had my druthers I'd give the buyer a partial refund, tell him to keep the book, and he can do with it as he pleases.
I know Adonis has had some issues in the past, but it's not his fault the buyer made assumptions on what he was buying. Bad form on keeping the book, IMO.
I agree with everything you say except this point.
If you're selling a raw book and the buyer continues saying "this will be a 9.8, right?", I think you have an obligation to temper the buyer's expectations or assume the consequences when it doesn't come back a 9.8. A-DONJS should have said something. Maybe his grading as good as he thinks it is which is something for everyone watching this to remeber if you'd still even consider buying something from him at this point.
I would place more value in that question if it came before throwing out the and sending the seller money, not after.
Donating the book to the raffle is a great idea, it would take some of the stink out of the situation.