Yeah, white people do racist shit all the time. But some of them fucking try to address it. Just like dudes do sexist shit all the time, but some are actually trying, or straight people do homophobic shit, but some try to be better, etc.
I'm not going to tell anyone who is Cherokee how to feel about it, but in general, Warren is trying to address her racism here and not to be racist in the future. If I cursed everyone who did something thoughtlessly bigoted, much less racist, to being a clearly lying shitbrick, I'd never talk to anyone ever.
That
Boss is using Warren's thoughtless bigotry as a cudgel to beat everyone reading over the head with "WHY IS SHE SUCH A HATEFUL LIAR JUST LIKE SHE LIED ABUT BERNIE" is the real disgusting thing here. Using the real pain of some Cherokee people to score political points is a real punk move.