Yeah, they are contradictory concepts to an extent. Making an uncensorable and untraceable protocol means exactly that. Things like the Fediverse are not that and censorship can come through things like defederation and blocking.
That said, they exist on different layers. You could probably run a federated system on top of this protocol and still be able to filter out the illegal and offensive content. It doesn’t mean that content just disappears, it just means you don’t have to subject yourself to it.