This is the logical next step for the left on this, isn't it? Well, let's slow down on it a little bit and look at their big-picture strategy, since the left often thinks it's won more people over to its point of view than it really has.
Objective: Convince the public that the police are the enemy, more of a threat to them than the criminals. I think this is more of a political narrative than the pursuit of any particular policy. It plays into the everyone-is-racist theme that gives the left the moral upper hand in the national discourse (or so they want to think), and once you've successfully tarred someone as an evil threat to humanity, the next logical step is to take away their means of brutalizing us. It feeds into the gun control narrative too, to be sure. The left wants to take away everyone else's guns, but up to now none of them dared to include the police in that concept.