This brings to mind the proverb chi di spada ferisce di spada perisce-literally, he who wounds by the sword perishes by the sword. Our "live by the sword, die by the sword." This is one of those sayings that has limited truth value. Unfortunately, there are plenty of people who are violent and destructive and don't get theirs, at least not in proportion.
Now the shoe is on the other foot for Al-Zaidi and he'll have to walk a mile in Bush's shoes. His fellow Iraqi was also clever to deploy the footwear in a country where he won't be imprisoned for it.