The guy’s obviously being sarcastic. He’s dealing with a white driver and she was reluctant to reach for her cell phone when he asked her for it — which isn’t as crazy as it sounds, as reaching for something in front of a jittery cop was exactly how Philando Castile got shot. The officer’s reply to her hesitation: “Remember, we only kill black people. We only kill black people, right?” That was dark, dark humor to assure the driver that he wasn’t going to spazz out and waste her for making a false move.
So dark that he’s now a national news story, penetrating the media consciousness as far as gossip sites like TMZ. Consider how tone-deaf your wisecracking has to be, as a mostly random joe, for it to qualify as national news.
The officer has been placed on administrative duty until he learns not to make jokes that are guaranteed to make him famous overnight, and not in a good way.