I don't know her personally so whether she's a supremacist or not I won't debate. What I know is that her arguments are valid on the matter. You treat police like shit (like black communities do) the police will likely reciprocate. You're disproportionately criminal, violent, or difficult to arrest the police will behave in such a way as to protect themselves. Just like deployed soldier to Iraq or Afghanistan have and they can suffer a kind of PTSD under those circumstances.
Tell you what. Let white cops police white neighborhoods and let black cops police black neighborhoods.
They tried that until the black cops got pissed at drawing shitty duty and sued calling it racist. ha ha