I appreciate Stevie for standing up for what he believes in, but Stand Your Ground has nothing to do with the Zimmerman case.
In some states, if somebody confronts you with violence, you have an obligation to run away if you can do so and do so safely. In Stand Your Ground States, as long as you are not the primary aggressor there is no obligation to flee. You can "stand your ground.
In the Zimmerman case, no matter if you believe his version, or you believe he should have been convicted it doesn't matter.
If you believe Zimmerman's verson of events, Trayvon was the primary aggressor. But SYG doesn't apply here because he says he was being held down on the ground, therefore he was not able to flee anyway and regular self defense rules apply.
If you believe Zimmerman was the primary aggressor and should have been convicted, SYG would not apply because he was the primary aggressor and you do not get the benefit of SYG in that situation.