I have mixed feelings about the essay as a whole, but that particular thing has always bothered me - Thompson minimizes how fundamental antisemitism was to the Nazi project. It was not just incidental; it could not just as easily have been targeted at any group!

Yep. And it's not just the miss on Jews, but also on everything else. Ambitious upwardly mobile people are scorned as obvious Nazis; downwardly mobile aristocrats are feted as the most reliable anti-Nazis. Thompson reported from Nazi Germany and somehow missed how the entire German gentry went Nazi.