Sorry didn't have time to read this entire 13 page thread, but we have only one data point to offer:
Last August we participated in a straight GB with 6 black guys, and none had an issue of any kind. They all seemed to have a great time, all in close proximity to each other. And this was a standing GB group in our area that had parties once or twice a month before COVID.
So we can't offer any blanket opinion on the topic, but it clearly isn't an accurate broad statement to say that one group or another is or isn't into something. It just depends on the participants. So if one is looking, just ask around
That being said, it literally took us years to find any kind, not just BBC, of established GB group in central NC, after seeing several back in CA. So availability may be regionally dependent as well.