I disagree with this line of thinking.
A thumb preview TGP is very similar to google's image search. While the preview images are hosted on google's servers, they are simply scaled down versions of full size images found on other sites that google provides as a convenience for their users.
Google isn't responsible for maintaining 2257 info for all the images contained in its image search.
Also, there was a lawsuit awhile back over whether showing a thumbnail on your site of someone else's copyrighted work was considered copyright infringement and the court ruled in favor of the website, saying that simply showing a thumbnail didn't violate the owner's property rights.
I'm thinking that would be used as a precedent for this type of case if it were brought to court.
