Public square access
I’d think that since SCOTUS said the internet and FB are part of the town square where you can assemble and discuss freely, they don’t have much of a choice even though they are a private company, but publically traded. That would tend to tell me, if you can express an opinion and discuss it with others on any internet based media, then anyone can access it for the express idea of sharing a thought.
If you are thinking of a class action lawsuit, then it may work. You cannot be part of the public square and restrict who goes there to speak.
Would have been better for the high court to say parents ought to be parents and watch their children’s online behavior too, but that was not the point of the case.