I can see the reverse happening too - let's say you're running a video game discussion forum and some guy decides to post illegal stuff in an obscure thread that you the owner are not aware of. But without 230, the owner becomes legally liable for the content that the owner did not produce nor was aware of it.

Not saying FB/Metaburg falls under that, but I can see the blade cutting both ways. What Fakerbergbook did was have it both ways: the government was directly involved with censoring content, and was aware of content AND allowed illegal stuff to happen (and was likely INVOLVED in producing said illegal content), BUT still was protected.