Lemmy is "uncensorable" and offers identical moderation abilities in the "public square" aspect. E-mail is "uncensorable". Uncensorable does not equal unmoderated. It means if you want to publish something, nobody, not the even the government, can stop you (though they can throw you in prison but that's outside the discussion of protocol). It doesn't mean anybody has to choose to listen to what you publish. It does not mean relays have to include you in their list of public tweets. Relays can pick what tweets/etc they show. They can choose what goes through their relay. What they can't do is stop you and another user from using the protocol to DM each other. As long as one relay allows your traffic through, the traffic will flow. They also can't stop you from tweeting, they can just choose not to show your tweets. If I want to follow somebody, frankly, it should be no business of a relay operator or the government or anybody to prevent me from following them, just like it should not be the business of the government to decide what books I am legally allowed to read. By building networks which are "uncensorable" we can guarantee that it remains not their business for future generations. So that they can live as free, or freer, than we do.
The internet, as a structure, is "uncensorable". This is good. Power should be decentralized. The whim of a government shouldn't dictate how the entirety of the internet operates, and it can't. People in power love censorship, it is to their advantage that we are not able to organize among each other using common communication platforms.