Pretty simple, if you ask me. I don't believe violence is the solution, so in my opinion, this is wrong. Others may disagree, but what they are doing is not okay.

Addendum: How would you feel if you were providing for yourself or your family, and your main source of income was attacked? That is frightening at the very least and very possibly dangerous. Threatening and frightening workers is not what needs to be accomplished. The big bosses don't give a shit if they have to replace windows. If you scare regular people who are just trying to do their jobs, you're doing it wrong. When we spread anarchist philosophy, we need to do so in an approachable, non-threatening manner. Being assholes doesn't help.