They cannot edit the database because they do not manage the users' private keys. All they have access to are the signed notes that users decided to give them, and the public keys to verify the signatures of those notes. And nothing stops the user from sending their signed notes to multiple relays.
Nostr detaches users and relays, leaving every note to stand on its own. This is in contrast to how ActivityPub strongly associates users with instances. As a result, Nostr users are more independent than Fediverse users, but in return they miss out on a lot of very considerable advantages of the Fediverse setup. Because relays don't own or control users, they basically have zero natural incentive to care about the quality of Nostr.
Also, all of the users on this gay platform are Bitcoin fanatics. Please send help; I'm losing my mind.