But that is astonishingly idealistic in the best case.

What happens is generational shifts over longer periods of time mean that draconian law or feature has more and more chances to be used by someone with bad intentions. It's the law of large numbers or murphy's law in full effect, it's not just 1 or 2 people.

I think we should distinguish between someone with bad intentions in a position of power, and the entire power of the state being taken over by people with bad intentions. The possibility of the former does indeed seem like a good argument for not building total surveillance systems. But I read the comment as talking about the latter.