[generalizations]

Replying to your first point, I think it's when Facebook adds their own original content. The bit of law quoted above mentions:

> shall be treated as the publisher or speaker of any information provided by another information content provider

Emphasis mine. I think that implies any information provided by themselves they're on the hook for.

[triceratops]

Which is fair enough. If they write a fact check that turns out to be libelous or illegal in some way, they are liable for that specific piece of content. I think the law is clear about that.

GP was saying something else entirely. They were contending that if FB moderates or fact-checks even a single user post, they are now the publisher of everything that users post on their platform. Which is not at all how the law works.

Platforms are still liable for content that they author and post themselves. They just aren't liable for what their users post, even if they perform moderation or "censorship" on those users' content.