Curious: why do we assume that having an anti-union stance is automatically bad? Can't someone simply think that union is indeed bad for both workers and companies?

Disclaimer: My personal view is that union can work for private organizations, but unions of government employees are absolutely evil. The reason is that a private company can die, so the power of its unions is naturally limited. On the other hand, government won't die (or die slowly), so its unions can issue all kinds of unreasonable demand.

P.S., If we assume that an employer is "bad" because it opposes union, isn't it the typical case of attacking one's motive? Scott Adam calls it mind reading. To me, it's one of the most dangerous fallacy in mankind. Read the history of self-claimed do-gooders such as Chinese/French/Cambodian committing genocide, and we can see the progressives in those countries all started with attacking their political opponents' motive.