>If it's all through a relay it probably isn't very censorship resistant at all. My messages may be signed locally but if the network trends towards mob-based bans and censorship like Mastodon as soon as I get on the wrong side of the network I'll be the only one seeing my signed posts

Well on their page they said" To publish something, you write a post, sign it with your key and send it to multiple relays (servers hosted by someone else, or yourself)."

If you really want to prevent that then it is to also selfhost.