[drewcrawford]

You misunderstand my argument, and OP's. I'm asserting something like "our children will be protected from firings when they express an unpopular opinion." This would be a regulation that applies to business, so the arguments you construct around business being a regulated sphere are actually arguments in favor of why this will happen. It is also a point that directly disproves OP's assertion that "the first amendment only applies to the government", because here it would be applied to the average employer.

[sanderjd]

As far as I know, at-will employees can absolutely be let go for expressing an unpopular opinion. It is only illegal to exclude a quite short list of "protected classes", mostly (entirely?) defined by immutable traits like race. To be clear, I don't think this "freedom to exclude" should be protected constitutionally the way freedom of speech is, and I'm a big supporter of all the exceptions to it that I know of, but I still think it's a worthwhile concept that should be considered when discussing freedom of speech as it pertains to private entities.

[MugaSofer]

This is currently true, yes. They're expressing hope/belief that this will someday seem unthinkable and strange.

[sanderjd]

You're right, I seem to have misread that comment. Too bad I can't downvote myself :)

FWIW, I don't necessarily disagree with that hope/belief, but I have some questions about how such a thing would work in practice. Clearly, some private organizations (like churches and political parties) rely on the ability to discriminate based on belief. But perhaps there's a clue there for how such a regulation could be drawn - those are not for-profit enterprises.