Get dirty with him right back. Find the IP range his scraper is hitting you with and set up a special page sent only to him which serves slightly different versions of
Goatse and ******* images. Or more beneficial make the image nothing more than your site's logo and url. Take his traffic. It's probably all automated so he is unlikely to notice right away.
If you want go further than serving special cloaked pages to just his known IP range and do something more versatile, implement a system to do it for any non-whitelisted bot. Set up traps to detect the bots. Just don't get the Googlebot or other beneficial ones by mistake.