The one saving grace of this incident is that the robber clearly had no idea how to shoot straight. Instead of being killed, the shop owner took one bullet to the leg. Not bad for an encounter where, disarmed by the people who are supposed to protect you and your rights, you have to make do with a club against a gun-wielding assailant.
You'll notice the robber realizes he can't hit the broad side of the barn and tries to get close enough multiple times to kill the shop owner. Fortunately, if you can't hit anything with a pistol (that is, you've never actually tried to practice with one and think everyone will just obey you because it's in your hand), a bat is a far better close-range weapon.
What is indisputable is that Chicago and strict gun control failed this shop owner and all its citizens. The shop owner should have had the option to shoot back.