There are reasons the formal definition of censorship focuses on the actions of the state. One of them is that decisions about which speech to carry or amplify (and which to not) in the context of private means are themselves rights of speech.
If you disagree, I look forward to you sending me your address and letting me put signs of my choice up on your lawn. After all as a principled defender of speech, you wouldn't want to "suppress" what I have to say by not giving me the privilege of putting whatever words I choose there.
The funny thing, though, is that even by your altered definition, what the ancestor comments are talking about here still isn't censorship -- even assuming that there's some basis on which to assume systematic click-to-read-more-ificitaion of "right of center" ideas other than "some dude on the internet feels like it might be true", it's not even that Twitter is taking the words down and making the ideas unavailable, it's that they're somewhat less convenient to actually read and you have to put extra clicks in. This has all the "suppression" of a downvote, a mechanism I'd wager you've recently used.
But hey. If you value discourse so little as to equate both "have to make extra clicks to read someone's hot take on some sites/apps (freedom to choose other sites/apps still quite intact)" and "face imprisonment for expression of certain ideas" under the umbrella of censorship, the good news is that free speech rights let you do that.
