I think it's entirely reasonable for someone to believe that the net result of a union in a particular place would be a negative for employees. They may be wrong, but holding that view doesn't automatically make them a bad person.

Maybe that does mean "you're with us or against us", but I'm pretty sure that kind of rhetoric only works to persuade people on the middle school playground, not in real life. At best, it will serve to convince weak-minded people who make decisions based on fear of being called names.

If you're going to try to convince me of something by telling me I'm an asshole if I don't agree with you, that's only going to push me away. That's just a fact, and if you want to convince me your opinion is the correct one, you need to focus on finding the argument that will give you the outcome you want, not the argument that lets you vent your frustration, even if "you're either with us or against us" is technically true. Because I don't care; if you're going to present your argument in that way, I'm very much fine being against you, even if I'd otherwise be sympathetic to your cause.

For the record, I'm fairly pro-union, though I do believe they can cause more problems than they solve in some situations. I'm commenting here because I'm really tired of people snatching defeat from the jaws of victory through self-destructive argumentation.