[1] https://www.cnet.com/news/fcc-rakes-in-45-billion-from-wirel...
You feel justified in controlling the behavior of a public company, not through the commercial code or any legal basis, but because you ex post decided the terms of service everyone agreed to upset you.
I don't think you should take for granted that this is true. Even privately owned things still must abide by the law of countries they operate in, and even that is just the most crude level of regulation and responsibility a public service has.
Yes, public service is still public even if privately owned. Anything operating open to the general public in this way has certain responsibilities (above and beyond the law) that go along with that. We live in a civic society and we depend on participants in that society living up to their responsibilities as citizens (including corporate citizens).
A lot of the problems we have in our society now result from the abdication of those responsibilities by the people (and corporations) that act in public without taking responsibility for those actions.
edit, for clarification:
my point is that private ownership does not remove a thing from social responsibilities. I understand that some people disagree with this, but it astonishes me that they do. The basic premise of civilization is finding ways to live together in ways that are a net-benefit.
Such as?
the current state of governance as well is strongly impacted by the pathologies of shareholder capitalism, which leads to businesses seeking to increase their private profits at the expense of literally everything else, including a scorched earth approach to legal regulation that serves the public benefit. the financing of climate-change denial propaganda campaigns by the coal industry is a very good example of this. another good example would be the private prison industry, and its associated lobbyists seeking to increase rates of incarceration.
this applies to individuals as well though, not just corporations. in many places, people have abdicated their responsibilities to their communities, seeking to live in walled off communities that have no interaction with "others" outside the barricades.
I could go on. I think you get the idea.
A better analogy might be to a broadcaster, who because of a monopoly on a scarce public resources, does have certain responsibilities.
But Twitter isn't a broadcaster (nor are they a public utility), and their value is in their network, which they literally have spent billions of dollars creating. It's theirs to do with as they see fit.