In a free society, individuals should be allowed to voluntarily choose who they wish to associate with, or not associate with. In an employment relationship, both the employer and employee should be free to terminate the employment relationship with or without notice, and for any reason or no reason – unless they contractually agree to something else.
In the recent case of the dentist who fired his dental assistant, the Iowa Supreme Court was correct in its decision to not penalize the dentist. The dental practice was the private property of the dentist. There was no employment contract between the parties, so the employment relationship could properly be terminated by either party.
People who disagree with what the dentist did are free to peacefully protest against the dentist, and they can try to peacefully organize a boycott of his practice. Remaining employees of the dentist are free to quit or to organize a peaceful strike against him if they wish. But, no one should be able to use force, even a majority through government, to dictate the terms of the employment relationship or penalize either party for terminating the relationship.
If a government had been the employer, it would have been a completely different situation. Governments are created by all of the people to serve all of the people. Government employers should only be allowed to discriminate based on factors related to job requirements and job performance. But peaceful people acting voluntarily should be left alone by government to decide for themselves whether or not to enter into any relationships with one another and to set the terms of those relationships.