Honestly, I agree with BLM: Bernie Sanders would do nothing for black people without significant prodding. He's the candidate of white, liberal, urban, upper-income para/professionals. That is, of people who aren't black and whose concerns are mostly non-intersecting with black people. These are the same people who presided over city and state governments, in the last decade, which acted massively against black residents through their police departments.
That's not because they're racist, it's because their priorities aren't the same as black priorities. What are their priorities? You're reading a white, college-educated person in the Bay Area with rich parents. Trust that I have basically no idea and that, if I ran the government, it would be very very easy for me to let those concerns slide. After all, my social circles look mostly like me and have the same priorities I tend to which are, as I said, probably non-intersecting. The concerns of black people aren't salients in my social universe and easily retreat into the background of "general injustice" where I can pretend my priorities also solve theirs.
So good: #BlackLivesMatter
has decided they're headed to the Forum to make noise on behalf of their interests to ensure they're attended to by the candidates. That's how this is supposed to work.