"Public" and "private" spaces are not so clear-cut. Not all public space is publicly owned. Again, see the shopping mall: https://www.minnpost.com/cityscape/2015/03/complex-role-mall.... As the article points out, the notion of "public space" is really a sort of conflict zone with ever-shifting boundaries. (If you remember "free speech zones" you can see how even fully public space gets attacked when protest becomes inconvenient.)

I completely agree that it would be impractical to legislate moderation or terms of service, except on maybe a very coarse scale. I'm not sure what the answer is. Like much in the political sphere, this may just be a space where law and litigation has to fight it out with private industry until the end of time. A "solution" that satisfies all parties may not be possible.

Thanks for the discussion.