If I understand it correctly, they can only ban the websites/relays or apps that use the Nostr network, but not Nostr itself, because it's a protocol, not a centralised website. So, I believe, if a government really want to ban Nostr, it's like killing a hydra (kill one, spawn two more) because there are thousands of relays and websites that are using the Nostr protocol. It's not impossible, but certainly difficult. At most, they can't shake down the network itself, but its users, so the gov must use fear and intimidation. Maybe works in certain countries, but most governments nowadays know it's a suicidal political move if they want to ban a protocol. Just my 2 sats.