But similarly, the property owner can't tell a person he may not have a gun after he leaves his private property, and an employer cannot dictate the speech and assembly of those in his employment when they are not "on the job."
A private property owner can say to someone, "If you have a gun
anywhere, then I will not allow you on my property ever again." Why can't the employer, similarly, say, "If you participate in a union, then I will never hire you?" The two situations appear to be analagous. In the one case, someone is being excluded from a piece of property; in the other, he is being excluded from a company.