This sounds like a very inappropriate joke, one you'd imagine cops telling one another in private. The speaker was likely irritated by the woman's fears and her implied accusation that he would use excessive force, so he snapped at her with a sarcastic, mocking affirmation, essentially saying 'Yep, those videos you've seen are right and all cops are racist murderers... but hey, you're white.'
If this was indeed a sarcastic joke, I think it matters to clarify that and distinguish this guy from the sort of officers who joined Arpaio's posse for the fun of tormenting Latinos (Latinxes?). So if I were defending him, which I'm not, I'd much rather say he slipped into sarcasm than that he was trying to "calm" her with this language.
If this was indeed a sarcastic joke, I think it matters to clarify that and distinguish this guy from the sort of officers who joined Arpaio's posse for the fun of tormenting Latinos (Latinxes?). So if I were defending him, which I'm not, I'd much rather say he slipped into sarcasm than that he was trying to "calm" her with this language.