I'm definitely not a union supporter - you can search my previous posts and see that; however I'm perfectly fine with them expressing their opinion on their badges if they like.
I did, however, find it within me to ask one of them why they don't just quit and go to another airline. The response: "They're even worse at other airlines..."
I dunno, I probably wouldn't be carping about being at the top of the food chain in my chosen career path. If I was unhappy with it, I'd be looking for a different line of work.