You're so close to getting it. It's a good analogy because you could equally say that each social network "is a home". That is indeed the case.
And yes, countries do indeed also get to choose their own laws through their own government process. I'm happy to live in a country where our laws forbid government restrictions on speech but allow private "homes" to make their own rules. I think that's the right balance. But I don't get to tell other nations what their laws should be.
You mean if the government of that nation censors speech that challenges the status quo? I think it's very bad for governments to do that, and would go to some length to ensure that the government of my own nation does not allow that, but I also don't get a direct say in what the governments of other nations do and how the citizens of those nations respond. I can certainly criticize from afar, but I don't get to vote or protest or fight to change the laws of those nations.
No. The private freedom of association is important. I'm similarly free to disagree with the choices the social network makes, as are you. But it is not bad for them to make their own choices, it's good.
And yes, countries do indeed also get to choose their own laws through their own government process. I'm happy to live in a country where our laws forbid government restrictions on speech but allow private "homes" to make their own rules. I think that's the right balance. But I don't get to tell other nations what their laws should be.