I'm not sure if I've got all of this, but sounds like you are not out any money and the seller just changed his mind for whatever reason(sold to someone else, donated, whatever). To take someones name and contact information and post it all over the place because he changed his mind seems like slander. Ebay has its own feedback mechanism just for such things.
Unless you've been defrauded, that's b.s to put someones private information up on the web and run them through the mud. Just my thoughts