> That degree of moderation, for that purpose, would make you liable if you left illegal or tortious content up i.e. if you moderate, you're a moderator, and your first duty is legal.

I'm not sure that's quite it. As I read the article and think about its application to Tiktok, the problem was more that "the algorithm" was engaged in active and allegedly expressive promotion of the unsafe material. If a site like HN just doesn't remove bad content, then the residual promotion is not exactly Hacker News's expression, but rather its users'.

The situation might change if a liability-causing article were itself given 'second chance' promotion or another editorial thumb on the scale, but I certainly hope that such editorial management is done with enough care to practically avoid that case.