Singer was quoted as saying “I strongly disagree we live in a white supremacist culture,”. Your quote implied that Singer was making comments about white supremacy, and Singer's reply to Casey Newton primarily focused on white supremacy in America.

I wasn't at the meeting, and it sounds like it was extremely charged. I don't think I can make nuanced comments about what was said there. But it seems clear that Singer made comments minimizing white supremacy in America, even his emailed reply does.