I don't think Bouie is saying it's racism alone. But setting that aside. Why, exactly, to the latter question?
Why exactly are you so adamant that white working class voters, or really any voter, that voted for Barack Obama and not John McCain, or Mitt Romney, means they're essentially incapable of finding racist and xenophobic rhetoric that Trump based his candidacy on appealing enough to vote for him?
Okay, I think you are confusing two different concepts and it is immensely important you do not, so I'm going to try really separating those two concepts.
There is someone we'll call Racist A. Racist A is, at core, racist. There is no a priori reason for their racism. It is a fundamental belief of theirs, that does not depend on any other beliefs. Regardless of any other fact or explanation, they will continue to be racist. It is their sole motivating belief. Racist A did not vote for Obama. The world in which McCain won allowed more racism to occur than the world where Obama won, so they voted McCain. These people are fundamentally moral scum. There is no point in talking to them; they will never, ever vote Democrat.
There is someone we'll call Racist B. Racist B is not, at core, racist. A priori, they are worried about their livelihood, and their children's livelihood. However, someone has come along, and told them that their livelihood, and their children's livelihood, depends on them throwing out the immigrants and keeping the blacks locked up; and they don't exist in a environment that allows them to determine otherwise easily. Their sole motivating belief is that they want the best for their children; they are racist because they think it follows from that. However, if they believed otherwise (that racism did not follow from that), they would vote otherwise. Racist B could very much have voted Obama twice, then voted Trump, because Obama convinced them that the solution to their problems was not racism, and then Clinton failed to do otherwise. These people are morally bad, but they're *not* irredeemable. It is enormously important we talk to them; they can vote Democrat, and more importantly, they can not be racist.
I think that an *enormous* portion of those who supported Clinton want to pretend
everyone who voted Trump is Racist A. And don't get me wrong, there are an awful lot of Racist As, and they did vote Trump. But there are also a lot of Racist Bs, and we need to do something about them. Not just for their sake, either - this isn't apologism, what they did was morally wrong - but for our own. Because without persuading them otherwise, minorities are in grave danger.