Oddbean new post about login | logout It's more a question about devs working on Bitcoin Core but at this point nodes are so decentralized that they will refuse to run software that is dangerous to the network. Hard Fork is always an option. I know it's not quite the same with Nostr though.
Nostr doesn't have a Core because it's an open protocol and not a blockchain. Bitcoin is a closed protocol and a blockchain. And there's no such thing as a hard fork on an open protocol because there is no Core to fork off of. It is an organic system held together through the value added by interoperability.