jecasc - 7:47 am on Oct 22, 2012 (gmt 0)
Bottom line, you screwed up and the receiver is under no obligation to return it. It is one of the costs of doing business. Learn from it and move on.
Have you even read the text? This refers to when the BUYER notices the error and the seller has not. Even in this case the text explicitly asks the buyer to contact the seller to arrange a return. Only if the seller does not react then the buyer can keep the goods.
So the FTC says the opposite what you are saying - the buyer has an obligation to cooperate in case of an honest shipping error.
In this case the seller has noticed the error and has asked the buyer to cooperate in the return of the goods - like it is his obligation.
If I were the OP I would give the buyer a reasonable amount of time to return the goods and then bill him for the goods.