I think the trickier question to answer, is whether concerted campaign could hurt a commercial relay? Reading this thread made me wonder if paid relays will ever work. My reasoning goes like this. Everything that's been said applies to free relays, but what happens if a commercial relay is targeted? A lot of paying customers won;t want to pay for a relay with that reputation, so there is a good incentive to target paid relays this way.
Having a reminder in the docs "do not pay extortionists, ever" might be a good idea, reduce the incentives to attack and prevent a financially-motivated attacker from getting a self-sustaining operation going. It will remain a risk, though, just like there are ideologically-motivated attackers who dDoS Tor at their own expense bcoz "free speech is right-wing extremism" etc.
But they have to pay to attack.
And you think nation states won't do that?
It's the same game theory as Bitcoin. Attacking it means paying the people that run the things... It's a futile effort. There are much easier things nation states can do to target specific relays. Again, it doesn't effect nostr if one relay goes down what's.
As you said that I was wondering whether the #GFC admins have figured out how to block #nostr #relays by protocol behavior as they've done with #signal. From what I've read it depends how simple the protocol is. #xmpp is hard to block even for China because it's so simple, but most others are a done deal already.
nostr is extremely simple. It's all just json being passed around websockets