Yep. It was an acknowledgement that the expectation among black citizens is that cops will be white supremacists, to the point where one “acting like” that works as a sort of camouflage that normalizes their interaction.
Although the other aspect of this is that in all likelihood she wasn’t telling him to do something he wasn’t otherwise normally going to do - she was making sure he would play it up.
Maybe the problem isn’t just that individual cops are white supremacists, but that the entire goddamned system was built by and for white supremacists to maintain white supremacy. Every single white supremacist cop could be fired tomorrow, and once we hired new cops to replace half of the police force, we’d still have a white supremacist system.