For some people, it is very much a moral choice. If you think that it is immoral to support Nazi's, then, well, that's pretty much the end of the conversation right there. Doesn't really matter if the person who is a Nazi is a shoemaker or a game maker or whatever. By buying things from that person, one is supporting them and thus supporting their views, even if it is indirectly.
For others, it's more of a separation. The author and the work are separate and should be judged separately.
And it's a really, really complicated issue that gets very heated, very quickly. Because, well, where do you draw the line? How much of modern technology is the result of Nazi scientists? All those scientists that got snapped up after WWII - they weren't all being forced to work. Some of them had to be Nazis as well. Do we boycott flying on a modern aircraft? So on and so forth.
I'm not pretending to have an answer here. The answer will always be personal. I don't really blame either side of the issue here. It's just something to keep in mind when talking about things like this. Respect works. Keep up the conversation, but, don't denounce or attack. Or, at least try not to anyway.

Be kind to each other.
My personal view is that the best thing for things like this is to hand it to creative people that the creator would absolutely hate and have them bring it forward. Let some gay, black female, immigrant writer publish Lovecraft stories and celebrate her. Support the authors that can take the good ideas of the work, strip away all the stuff that makes it an issue, and bring it forward. It's the best kind of revenge in my mind.