My wife has never been forced to publish anything against her will. That being said, she has disagreed with the editorial decisions of the paper on a number of occasions. This is not at odds with the freedom of association; every single organization is comprised of individuals that don't always agree with one another, but work together to overcome their disagreements. Nowhere has there ever been a guarantee that the freedom of association presupposes that every individual has the freedom to confer the exact same set of opinions to everyone in their association. Importantly, my wife doesn't feel like she's entitled to the power to censure other journalists or employees in her company. I know that I don't have the power to do that in my own company, nor should I.
There's disagreement within every group, that doesn't render the concept of free association invalid. The Catholic Church has its disagreements, but that doesn't mean that they lose the freedom to congregate because they're somehow no longer a bona fide association on account of that internal disagreement. The Democratic Party has its disagreements (heaven knows), the Republican Party is essentially at war with itself, the Libertarian Party can never agree on what it stands for because it's a motley crew of weirdos. None of this matters, they are all protected by the First Amendment, as associations. Whether they are traded on the NYSE, or they are 501(c)4 non-profit corporations, or they are just an amateur club, they are protected by the same First Amendment, and are subject to the same narrow limits on speech established by Brandenburg v Ohio (and all other relevant precedents).
Obviously the transaction cost to quitting and finding a new job is not zero; the Constitution's protection of the freedom of association has no guarantees on what the transaction cost to associate are. Just like free speech, you're free to say whatever you want, but you're not entitled to a free platform; promulgating speech costs money. You're free to keep and bear arms, but you're not entitled to a free rifle; guns cost money.
Associations are more than capable of gross misbehavior; but in manners related specifically to the publishing of speech and expression, they enjoy outsized protection, at least in the United States.