I remember reading this when it was published, as I was living in a college dorm at the time and strongly considered using this method to produce a master key. I didn't, because I couldn't think of anything I'd want to do with the master key once I had it. But I enjoyed knowing that I could make one if I'd wanted to.
I had plenty of legitimate uses for a master key, but I didn't make one because once 2 or 3 people know you have a master key you get blamed for every single misplaced object in the whole damn dorm.
