That is why the problem is not corporations' ability to fire employees, but whether that corporation is a monopoly, i. e. that employee's only option for employ

That is why the problem is not corporations' ability to fire employees, but whether that corporation is a monopoly, i. e. that employee's only option for employment. For a corporation with competition, the ability to fire someone over disagreement is clearly reasonable, since that employee may prefer work with another corporation in that sector. To contrast: For a monopoly, the ability to fire someone over disagreement, and no other merit, is suddenly transformed into an abuse over free speech. The employee can't speak out against a monopoly, and expect to find work afterward, meaning that employee has poignant reason not to speak out in the first place.