In the post, they mention that each board will be moderated (filtered) by the creator, and the same goes for thread creators. Effectively it comes down to content creation and filters that can live on the client-side.

Any decentralized unauthenticated or federated social network faces the same issues around reputation, moderation and sybil attacks. Matrix, for example, has the same.

I imagine over time we'll get a growing economy of curation markets - users choose their own maintainers for allow/deny-lists and content discovery, effectively allowing them to use these networks in a way that is meaningful to them.

Some of these mechanisms are explored quite heavily by people in the Ethereum space - not necessarily with social networks in mind, but I think these kinds of mechanisms are going to play a more important role in our world in the coming decades (lest we go deeper into centralized control)