Moderating content is explicitly protected by the text of Section 230(c)(2)(a):

"(2)Civil liability No provider or user of an interactive computer service shall be held liable on account of— (A)any action voluntarily taken in good faith to restrict access to or availability of material that the provider or user considers to be obscene, lewd, lascivious, filthy, excessively violent, harassing, or otherwise objectionable, whether or not such material is constitutionally protected; or"

Algorithmic ranking, curation, and promotion are not.