> The cases I listed above all involve sole proprietorships or closely-held companies, so compelling the business to engage in protected speech is tantamount to compelling the individual who owns the business to engage in protected speech.
The moment you start a business you adapt an additional role to the one you already have ("private person"). In this role you have specific rights and obligations while you're in that role. It's the same reason that a person who is a police officer is allowed to arrest you while on duty (in his role as a police officer), but not when he is off duty (and in his role as a private citizen).
I agree the states and Congress can regulate commerce, but those regulations are still subject to the First Amendment.