I can’t find the article, but the buyer had stated that Sotheby’s mostly reimbursed him. Maybe he was out shipping or VAT? It also said, the buyer, an Italian lawyer, technically could have kept it, but chose not to.
If it were me, I would have made the exchange contingent on eventually getting the forgery in return once the case was closed.
Presumably it technically was “given” to the hotel.
The auction house is a facilitator of a transaction between the parties. Unless they purchase the object from the seller first, they are not even a middle man. They are akin to ebay, a platform rather than a dealership. I'd bet that somewhere in the fine print is even a statement that any appraisals remain the opinion of the individual appraiser and are not the responsibility of the auction house.
https://www.theglobeandmail.com/politics/article-italian-who...
I expect that's the statement of a lawyer in CYA mode; at some point he goes from unknowing victim to knowingly holding stolen property, which can start to cause legal issues.