Nostr is a protocol and basically just set of rules around which people build different apps. No one can stop nostr but you are right about apps and relays. In future I am sure we're gonna see many such cases.

If I run a relay which propagates illegal content and the government decides to fuck me - I am fucked. Before locking me up they might try to put a pressure on me to reveal the IP of the users who distribute illegal content and if I am unable or unwilling to do so - I am fucked.

From the users perspective the only way to use nostr absolutely privately and anonymously is though tor as all relays are aware of users IP addresses.

But the thing is - anyone can run relay and the most important thing is to decentralize relays as much as possible so that there is really no "one head to cut off". And I am sure they will try to intimidate replay owners buy fucking up some people as an example eventually.