> It is privately owned, but it acts as a public square. For the same reasons that we defend the right to Free Speech at the public level, we should push the platforms that act as public squares to guarantee Free Speech.
I disagree.
Free speech means that no government has the right to tell content publishers - in this instance Twitter - what to and what not to publish, modulo the standard legal exclusions of child abuse material and incitement. (This viewpoint changes if we're discussing a common-carrier or a natural monopoly, where universal service obligations are necessary).
On the Internet, it's the Internet itself which is the public square. The content publishers like Twitter are merely commercial operators of 'printing presses' which make their material available to information consumers/citizens within that public square.
Content publishers should have every right to censor/reject/moderate any content submitted to them. If the content submitter doesn't like this, then they too can spin up their own content publishing platform on the Internet and publish what they desire.