to be listed on Mastodon’s official site, an instance has to agree to follow the Mastodon Server Covenant which lays out commitments to “actively moderat[e] against racism, sexism, homophobia and transphobia”, have daily backups, grant more than one person emergency access, and notify people three months in advance of potential closure. These indirect methods are meant to ensure that most people who encounter a platform have a safe experience, even without the advantages of centralization.
Some of these baseline protections are certainly a good idea. The idea of advance notice of shut down and back ups are particularly valuable.
I'd not know of the Mastodon Server Covenant before.