Hostile to whom? People who deny the existence of systemic and institutional racism?

> As a non-white person I would have been extremely uncomfortable sitting through that.

Why? I ask because I'm also a non-white person who has sat through just those kind of discussions. They weren't "comfortable" - no introspective discussion of racism is - but they certainly were not hostile because the participants came with charity and a desire to understand themselves and the context better.

The tone of any conversation, defined by the attitudes of those who participate, has a great deal to do with the way people experience it.