Garage band EvilWebsite.com is going to appreciate that 5$ way more than the SPLC or whatever.
This isn't to say that the policy is strictly bad, I just worry that it reinforces pretty negative patterns. Carbon offsets barely work, and that's an actual market - bigotry offsets are a dark line to walk.
(edit - misread the policy; it's not about matching cash flows through the service to offending websites, it's donating profits from offending costumers. That seems more consistent to me.)