It's tactic I approve of because they're introducing violence into what should be a voluntary arrangement. If they didn't get special legal privileges as a union, then I'd be against it Walmart discouraging it. When someone starts unionizing, unfortunately in the US they're inviting the a man with a gun to the negotiating table - it no longer is a voluntary agreement. For instance the government can force companies to deal with union negotiations even if the company doesn't want to; you can't fire people for striking; you can't file trespassing complaints against union members, etc. I don't know about you, but when I'm working with someone - I want it to be amicable and don't want them strong arming me. If I think they will then I'll choose not to work for them, I see no difference here.
If this is the attitude you have going into a union negotiation, you're not going to reach an agreement. When I'm negotiating with someone, I want them to be amicable and not accuse me of being "the man with a gun".
