The 'right-to-work' doublespeak wins again. Horowitz is right (I think) that this behavior may violate California labor laws but he used the wrong term. The article you linked to explains what I mean but the gist is that right-to-work laws are laws that restrict union organizing in various ways.

Edit: It's not actually very relevant to this discussion but to the extent that it is, the fact that California does NOT have such a law means that workers have more rights than states that do.