to any extent that a relay could be a point of failure, there can always be another relay out there serving up that same data.

Assuming you're not posting to only a single relay.

The protocol doesn’t rely on a trusted central server; instead, all users run a client. Using this client, users publish content by writing a post, signing it with their private key and sending it to other servers which then relay that content along. The relays are simple: Their only job is to accept posts and forward them along to relay participants. These few servers could be censored / shutdown. One could set up new servers....