hybrid havoc

This is frankly bizarre. I don’t understand how you can even write that and reasonably think that the platform hosting the hypothetical defamation should have any liability there. Like this is actually a braindead take.

Not how it works. Also your use of “becomes a publisher” suggests to me that you are misinformed - as so many people are - that there is some sort of a publisher vs platform distinction in Section 230. There is not.