What do you want racists to do? Not vote? They're gonna vote for somebody after all.
As I pointed out in a different post, trying to shame people into silence doesn't magically change their vote.
Unfortunately, when you are going to call every Rep supporter a racist with no evidence other than who they voted for, they are going to stop answering your polls honestly.
Still not gonna change their vote though...
Going back to the original quote, you need to see that it's not calling all voters a particular thing. There's a simple Venn diagram, one circle of racists inside a larger circle of a particular block of voters.
Educating people out of racism, and removing racism from your society, will change votes as racism is only one aspect of a person's beliefs.