As for sending referrers when spidering a page, that doesn't really make sense. If you have 5000 inbound links, do you really want Google to request the same page 5000 times with different referrers? Robots aren't browsers and they generally don't follow links. They just add the linked-to URL to their database (if it's not already there) and it'll get spidered along with all the rest at some future date. The problem is that Google is associating the content returned for the target URL with that URL and all URLs that link to it, rather than simply recording the fact that the redirect URLs are redirects and ignoring them when generating search results.
Perhaps the Request URI can be checked on your site, if it does not match the page you serve a blank page, this could work, I'm going to go check if google actually sends the wrong request URI with hijacked pages.