This has always been the case. Book publishers can refuse to publish your manuscript, newspapers don't have to post your reply. Censorship in one form or another has always been there.
"No provider or user of an interactive computer service shall be treated as the publisher or speaker of any information provided by another information content provider"
Therefore the correlation does not work.
Part of the intent for section 230 was to allow free open discussion without the platform being liable. But once they begin to curate the content ( nice way to say censor ) they are no longer performing under section 230.