The whole reason Nazis are bad is because the violence they espouse may come to pass.
Nazi's are bad because their ideology is bad. Even Ms.Galaxy realized it was bad after years of supporting widespread genocide.
You don't say! No kidding, you dolt, and the reason the ideology is bad is because it threatens to harm people. If you could see into the future and know for 100% that Nazis would never get any power or hurt anyone, their ideology would be as inert as the guy on the corner with a sign that says "The end is nigh." It would be completely empty. The ideology is bad because of its potential to spread and manifest in the real world as real actions.
Ms.Galaxy would never use a 1st-grade level tautology as some weak attempt at a gotcha.