[throwawaysea]

Sure but if both sides have the human right to freely associate, then the employer should surely have the right to reject associating with the union at all. But that's not afforded to them under US law, per my understanding.

[burkaman]

"Associate" has a specific definition here that's a little narrower than normal conversation. It refers to being a member of a group, not just being connected to it in some way. The CEO is free to not join the union if they don't want to. They can also quit if they don't want to deal with it at all.