Twitter is already a public company left to its own devices. But free speech wise, what Twitter needs is intervention. Scott is plainly in the same bubble as the existing Twitter employees and can’t provide that intervention.
Musk made his comments in context of social networks. In a digitizing world where all conversation is centered into a handful of platforms, those platforms become the free speech carrier, no matter who owns them.
Yes, you're technically correct, but it's irrelevant from a pragmatic point of view. A legal definition of free speech is worthless if said free speech cannot be expressed in the places where most speech happens.
You can argue that major platforms like Twitter are essential to free speech, maybe even persuasively. What you can't do is make your case as if it were a self-evident fact. It is not.