"German de-Nazification would be called an ideological tyranny if it were ever objectively described, and it brainwashed a generation of Germans. The German soul of romantic discomfort with the modern world was murdered, with disastrous consequences for European culture. Liberal democratic cosmopolitanism didn’t win any arguments; it won a war, and got to impose itself by force."

It reads like the writer is trying to say something, but isn't really concrete about what that is.

Without any concrete criticism of "Liberal democratic cosmopolitanism" it's hard to know what this is trying to say. As others have done in the comments, this vague language leads one to guess what they mean. The principle of charity should be used, but it's hard when the same complaints are often used as a dog whistle by the extreme right.

What exactly is the problem with de-nazification? Explicitly violent and genocidal isms like Nazism should not be tolerated in good faith discussions. They should not be "debated" as Equal viewpoints.

To call it brainwashing is a stretch. Nazism has lead directly to millions of deaths in the name of Nazism and not something else. If that's not something we can agree to fight, then what is?