>If you see the actions of Twitter, et al. as stemming not from a desire to flex power over society
Except I don't see that as being the source at all. Like I said, the support for these initiatives originates in government. Hence the government making much of their intent to further legislate and examine the operating models, algorithms, and moderation of these companies. Twitter, Alphabet, Facebook, etc are all acting defensively in response to these pressures, but in the process there's very little appetite to defend free speech proper (even the ACLU, I am given to understand, is not the same organization that at one time defended the KKK's right to march in the streets - although I can't remember too much of the noise around their supposed change in direction). The ratchet only ever goes one way.
Other companies are already modifying what discussion is allowed or disfavored on their platforms, as I noted in my post. They can see the headwinds clearly. As more governments discover the power of controlling the narrative, it will only be natural for them to apply pressure to companies that have the greatest power to modify that narrative. Institutions follow incentives just like every other agentic thing. They have an incentive to defend themselves and accumulate power, and so it is often useful to model them as (usually) taking actions that help them do that.
Note that I'm not saying that the President is going to call the CEO of Twitter and tell him, "Stop this whole 'Let's go Brandon!' thing." That's not really how it works. To paraphrase the editor of the NYT (iirc), "I've never had to kill a story my journalists wrote for political reasons." And neither, probably, did the editors of Pravda. Once you get to a certain level of awareness, and it's hard to believe the C-suite of these large tech companies lacking that, you have to be able to read the room, politically speaking, and know what the actual big players - the people with the real power - want out of you. Subtle alterations of reported reality is going to be the new normal. "What you're hearing and seeing isn't really what's going on" - a bit more terrifying to realize that that's the capability that's slowly becoming normalized.