"Free speech exists as a protection from government censorship"

So what happens when the line between government and corporation is blurred? The common justification why that corporations aren't beholden to free speech is that you can just choose another corporation to spend your time/money on.

What if you can't choose? What if it's prohibitively expensive to just setup an alternative (perhaps due to regulatory capture)?

What if there's no competition because corporations have subtly merged with government?

Maybe it's simply just not right anymore to assume that if it's a private organisation that they're exempt from societal/governmental principals.