Turn it around. Not "Facebook knows things about you, therefore Nazis" but rather "Nazis existed as a historical fact, therefore what Facebook knows about you is incredibly dangerous."

Your thesis seems to be, right now things are good therefore at no point in the future will a 'bad actor' government make Facebook comply and facilitate whatever they need to fulfill their goals. Matter fact, there could be a long term scenario were the company gets nationalized or the data centers confiscated and that's the end of it. This is why other countries don't let foreign social networks operate in their 'digital soil', they are aware of the power of it.

The irony is that this same mentality of 'everything is good' was the same mentality that people probably had when they walked over to auto-register on the census as Jewish back in the day. They just didn't see it coming. If we can learn something from history is that every 100-200 years the status quo gets thrown out the window.