Personally I think making them public square is probably the only real solution if you want to keep social media and avoid this drama, or make them liable as publishers and these platforms will disappear overnight (maybe the best result?!?)...
This carries over into LLMs I presume, which have bias and I assume are not being sued for the content the publish? I'm not really sure about how it applies to LLMs to be honest.
Regardless, other countries will have different laws, that have different takes on censorship and what private companies are responsible for.
I don’t see this as a problem. They could just as easily have changed their business model and invested more heavily in content moderation. Maybe it wouldn’t have been as profitable, but profit is a great motivator to do bad things.
[1] Of course, that was plainly censorship with a veneer of plausible deniability (it assumed those embeds could only be truthful and unbiased and in no way politically motivated).