What's the difference, in practice? Not only
can the corporation fire me for putting such a label on the food, they
must, if such a law exists - if they don't, they're liable.
So, let's say I'm a baker selling, I dunno, kosher cookies. I can sell them to my friends and say, "By the way, these are kosher!" They're popular with my friends, and so I decide to make a business out of it. As soon as I do that, the business is never given the right of free speech, and the business is now given an obligation to prevent me-the-individual from saying certain things in the course of my job duties. That is, if I continue saying the same thing I said yesterday, the government can shut down my business.
You'd say that this is constitutional?