As long as it was plain shipping, the shipping cost included a round trip if the item is not deliverable or refused, eg, there is no return shipping fee. (COD and packages with special handling charges are different) Of course, he will have to pay them again to ship it to you after it comes back...if he is clever, he will redirect the destination address in transit, it's messy, but often cheaper than getting it back and shipping it all over again if the item is large.
Interestingly, if USP has to correct the address to deliver a package they charge you for that little service..
>I am a little concerned that he will tell UPS just to keep them...
Only if he is an idiot, they *do* charge a disposal fee....