You have to remember that "corporation" can mean any group organized for a purpose. It can be Exxon, but it can also be Planned Parenthood or AARP.

People who can't speak loudly enough by themselves have a right to organize into a corporation, pool their money, and speak loudly together.

You can argue that a business should not be both a commercial enterprise and a holder of 1st Amendment rights, but that's not what the law says. And anyway, it would be an impossible line to draw.

I was responding narrowly about the idea that "free speech" demands that the US govt can force companies to choose what to publish.

Forcing a company to stop operating here is an entirely different concept.