It more like the opposite. Federated instances can keep all the federated posts without ever deleting them. Then also sell and monetize it.
anyone can start their own community instance and kill it on a whim.
Shutting down an instance doesn't mean it's censorship. If a library shuts down if it can't stay up, is that censorship?
It's a lot of work to set it up and sustain that type of situation, so it's not realistic for a rational person that does not have a severe internet addiction to waste their time and effort doing it.