Tony Martin is nowhere near as bad as George Zimmerman. Tony Martin killed a guy who broke into his house.
It's true that the kid killed was fleeing at the time of the shooting, but there's still a world of difference between killing somebody who broke into your house, and killing somebody for no real reason at all. Especially when George Zimmerman called 911, was specifically told to stay inside, but chose to ignore that. He went out looking to cause trouble.