True. It just pisses me right off when people try to cause controversy in the guise of improving race relations. BLM has shot itself in the foot multiple times thus far.
I don't think all forms of controversy are made equal though. There was an article comparing the rally shutdown to the Montgomery Bus Boycott and the March on Washington, but I think that's a false comparison. The Montgomery Bus Boycott was a visible disruption of a single part of society where black people were the most visibly discriminated against. It just made sense as a part of the Civil Rights Movement, a demonstration against an arm of a larger institution working against black people.
To me, this particular demonstration didn't seem deliberate at all. I think that they took the opportunity to shut down the rally because they knew that there would be many people there and that they would get on the headlines. There's not any sensible explanation for why they chose Bernie Sanders' rally instead of another candidate's. It's just a publicity stunt for them.