i don't know how governments would ban nostr though. you ban 1 domain and boom another on pops up. clients and relays would always be popping up. plus, people would be running clients on their phones and home computers. it's a game of whack-a-mole. it can be hindered, but not banned, imo.
Discussion
Don't need a ban, just a threat of severe punishment like imprisonment would be enough to scare off many relay operators.
It would have to be a blanket global ban though right?
Federal law enforcement has a wide reach on the web. All they need is to cooperate to take down a few key relays abroad and that will send a signal that anyone is up for grabs.
Personally, I think they’ll be up against it not only logistically but also legally. They’ll have to be extremely specific in relation to what a relay is and how it’s “bad” without crossing into other perfectly legal uses and definitions. But who knows. I’m no expert.