> Censorship can also describe private actions such as Twitter/Facebook refusing some ideas,

That's only true in the vernacular. True "censorship" is only relevant to government suppression. Individuals or private corporations are under no legal obligation to allow certain ideas/topics.

*That is to say, I could perfectly well create some new social network messaging app that specifically does not allow any posts about honeybees, screwdrivers, or Turkey. The government could not prohibit those topics.

> Individuals or private corporations are under no legal obligation to allow certain ideas/topics.

(Though it does become problematic as communication channels are concentrated in a few parties hands, which is why, in part, we have things like the common carrier doctrine. In the end, if one party accumulates enough power and uses it in a way that it is oppressive, whether that party is a government, a warlord, or a corporation).

I'm really not a big fan of this kind of moral relativism. The US (though Donald Trump seems to want to) does not "blacklist" or "censor" to silence political dissent. China does and always has, heavily, to the point of nonsense.