Hector Martin on Nostr: Indeed it "could be argued", but as far as I know it hasn't been argued, and it is a ...

Indeed it "could be argued", but as far as I know it hasn't been argued, and it is a very difficult thing to argue. "Public performance" of a copyrighted musical work implies transmitting that work over the air to an audience: the work itself is transmitted. Hosting a service doesn't do that.