Too much attention on this one to go quietly into the night until some finality occurs. There are only 2 outcomes, Cav will get this book or he won't. Once either occurs it will subside.
TBH I wish the mods had not moved this from the sales forum...
There is a third outcome. Seller pays Cav the difference in sales price (his additional profit), plus perhaps a penalty and/or interest and/or extra to cover the taxes (I think it would count as income to Cav and therefore be taxable technically).
I think once the book is sold (paid for and shipped) to another buyer in good faith (assuming it was good faith), its pretty tough to compel that buyer to give the book back.
I don't think it was confirmed he sold it to someone else.