That's fair. The "I only sweep floors, if you want mopping it's another department" type of union inflexibility is terrible for productivity. But I think your scenario is an example of inflexibility that's completely warranted.
The next day I was in his office when we got a nice visit from the Teamsters steward flanked literally by two huge guys glaring at us. The steward told us not to do it again. He did back off when we told him we walked the computers between the buildings - if we would have drove them between buildings he said they would have filed a union grievance.