For the anticommunist power-posters, I think what you're saying makes sense, but a lot of people have a similar (less overstated) reaction from a much more casual perspective, and for understanding those people, I have a comment: There has been a project for 80 years now of tarring communists, the USSR especially, as being equivalent to Nazis. It is ubiquitous and you rarely ever see a specifically contrary claim. It makes sense that at least some people would just shrug and accept it. Given that, imagine being told "Actually I think history is nuanced and that we should look at it with a critical eye, avoiding oversimplification" regarding people who you believe were as bad or even worse than the Nazis; isn't that like someone saying that about the Nazis? Like those people who want to rehabilitate Hitler or deny the Holocaust? I think most of us would be appalled.

So that makes it more challenging to figure out how to address those people, who are really the only people worth addressing because the power posters aren't listening.