I believe once the line is being crossed about whether the player knows they are being talked about is honestly the turning point. I can't seem to find any clips of what was going on exactly, all of them have been deleted now - but from what I understand, the BLM in the group was also being an ass, and sassing him a bunch.
BLM was most likely in his stream as well, and when you start doing things like this:
(without the red box, I added that)
You are pretty much asking to be banned by SE.
He also apparently had some sounds that would trigger when the BLM messed up or something, and received donations from viewers also shit talking the blm.
This isn't even the first time he's done something like this, but I assume it's more of a character he plays up.