The government, by definition, holds the monopoly on legal violence. This is the fundamental difference. It isn't a big corporation. But firing the guy because

The government, by definition, holds the monopoly on legal violence. This is the fundamental difference. It isn't a big corporation. But firing the guy because he said X is where the free speech line is crossed. There are people who argue employers have the right to fire anyone for any reason because of their own rights. The current reality in the US is that people are routinely fired for even mentioning the concept of a union in the workplace. I agree that is against the ideal of free speech, but not the law as it exists. The thing I have noticed over the past year is that many of the same people who think it's great to fire people for collective action suddenly get very imaginative about free speech when it happens to people they agree with.