OK, that's pretty cool. I like it.
BTW, if you click these images they give attribution when shown on the right hand side, which all appeared to be from the wiki, which is a common usage license, making the issue moot if they only use those images. Besides, if you watermark your images (which everyone should) it's great exposure, if not, too bad.
IMO, if you allow any SE to index images, how they use those images in the promotion of the content is fair game. However, if they were using images from site A to promote content from site B, then we'd have a real problem and that's not what's happening here whatsoever. If you don't like what they do with your images simply don't allow them to be indexed.
FWIW, controlling content crawl and usage via robots.txt, .htaccess, robots meta, robots headers, etc. is easily doable so nobody is stealing much of anything anymore unless the webmaster permits it to happen. If a webmaster doesn't know how to do these things that's another problem, but not the SE's problem as all the tools you need are there if you know how to use them.