self-defense statutes was justified... That includes walking up to Zimmerman and punching Zimmerman in the face...

If that is true in your country, I am amazed.

you say it's okay for Zimmerman to use the "self defense" argument

It is Bobert. Not just me saying it.

but not okay for that same statute to apply to an unarmed black kid being stalked by a larger man with a gun.
Try to take race out of it
It might be OK, but I doubt it would stand up whatever the colour.

You might well be right about Z's guilt, but you can not know.
Even the court has not heard both cases yet.