Sure, but then it shouldn't be allowed to hide behind Section 230.
"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"
Translation: they can "censor" or moderate or remove spam to their heart's content, even beyond what's legally required.
Without the safe harbor, activists could flood 2A message boards with "guns evil, ban them all" spam and the mods could do nothing to stop them lest they lose Section 230 protections. Trolls could harass users on religious or parenting forums or support groups for cancer, grief, PTSD, or addiction. Practically any Internet message board would become unusable.