Actually, I do think we should hold "peaceful" BLM leaders morally (not legally) responsible for tweets from their followers. How can a movement of justice accept the silence or ineffectiveness of BLM leaders with regards to inculcating a non-vile culture and calling out hate speech? Isn't tolerating that sort of thing from a movement's followers for the sake of internal politics and membership basically the same thing as tolerating a number of bad cops for the sake of "thin blue line" solidarity and internal police politics? It's not viable without becoming hypocritical. The only difference is in direct connection and legal consequence, not in the overall morality.

I think we can tolerate vileness as a culture and society, but we should not welcome it -- especially if it starts to abrogate what participants would consent to. We can't tolerate hate speech that incites to violence, period. We should not laud internet vileness as some kind of magical problem-solving "pure" expression, which is what we seem to be doing now. There is an important difference between a freedom and a virtue. Movements of social justice need to be teaching virtue. Otherwise, history shows us that such things will tend to devolve into demagoguery and mob behavior.