Just like AP, the bigot can join another instance/relay, if an instance has bad moderation policy, your relay can block that instance/relay entirely.
By your own admission, this doesn’t happen though. One relay is the same as the other, and that’s because the bigot can just use multiple relays as well, making the effort of an admin blocking them largely a waste of time.
They can do this in AP too.
They can’t though, because on AP, an instance that constantly spawns bigots with throw away accounts gets defederated, and that means that bigots have a barrier that doesn’t exist on Nostr. On nostr they can create unlimited accounts and use unlimited relays to broadcast their content, relying on the admins to block each and every account manually (which they generally won’t do, because what’s the point?), which ultimately leads to the end users having to play whack a mole with the bigots.
There’s no way to solve this unless we start requiring a passport photo with every account or a payment or something
I don’t have any answers for you. But I can tell you that I actively prefer APs implementation to Nostr’s because APs current implementation is safer.