On an AdSense supported site, it would put the advertisers "at significant risk." It would very likely get me kicked out of AdSense, if I left it (and they'd be justified in doing so). This is not an affiliate site, it's a community service event site. At peak season, the site sucks up an enormous amount of resources for a short period of time, which need to paid for, but the nature of it is such that it's not easily otherwise monetized besides ads.
I don't know if it's an attack, or a mistake, or collateral damage, but it doesn't matter, I still have bills to pay. All I can do is put it on another domain, non-redirected, and start over.