of course if the content of the community is illegal then government can go after the operator of the relay. but it would have to actually be illegal. loving Hitler is not illegal, yet you can bet your ass you couldn't have an "I Love Hitler" reddit. if they closed the Trump reddit they certainly would not allow a Hitler one.
my point is moderation is different from censorship, because there would not be any platform-wide ideology, like there is on Reddit, Twitter and everywhere else ( except Fediverse ).
and the problem with Fediverse is a user is tied to an instance and if the instance is blocked everybody on it is blocked. on other hand with NOSTR you would not be tied to any community in any way, so it would not be like Fedi and it would not be like Reddit.