He can just not see it. He doesn't have to get to robbery calls before the robber has escaped. He doesn't have to take chances chasing down a fleeing murderer. He can just be outrun. He can turn on the siren so that the bad guys will be gone when he gets there.
Cops have options.
And white cops don't live in black neighborhoods. They don't have to care what goes on. This sort of undeclared strike is absolutely racially driven. Cops in white regions still do their jobs. A white cop who stops a white drunk doesn't get sued by Jesse Jackson.