The movement is about the continued polarization of blacks against whites, playing on the intentional conflation of "cops" with "whites" with "racists" with "KKK" and "conservatives and Republicans".

As Democrats have run out of excuses for why inner city blacks live in poverty and hopelessness despite several consecutive generations of Democrat politicians representing them at every level of government, they must distract the black population from the reality of failed Democrat policies by emphasizing wedge issues, such as "racist cops" who use force when confronting non-compliant resisting black suspects (as if anything other than force is a legitimate option for arresting someone who doesn't follow police orders).

You're either mistaken about the nature of the situation, or naive about its actual purpose. Police forces could ban all whites from street policing, and everything would still be the same.