Reddit can be held civilly and even criminally liable if it knowingly profits from material related to sex trafficking or sexual abuse. Continuing to host such material after a lawful request to remove it puts them within the range of the carve-out for sex crime laws in Section 230(e). The plaintiff asserts that moderators of reddit coerced sexually explicit material from minors, distributed it on reddit, and that reddit's paid staff failed to halt these activities once alerted.
@AnOminous can shed more light on this I'm sure, but Section 230 clearly states that internet companies aren't protected from civil cases brought under Title 18 Section 1595.