When you don't publicly dissociate your company/party/whatev from statements that are made by people associated with your company/etc, people will take that as tacit acceptance or approval.

Blizzard's initial response was awful, and they've done little IMO to walk back from that. However, they do have a right (and the responsibility) to enforce their policies. Hopefully, if this same situation occurs again, they respond with something less than the nuclear option.