See, here's the difference - Trayvon Martin died because Zim was playing cop. Zimmerman did not rob Martin, and I may point out that Martin was not robbing Zim either. The difference also was that Zim claimed self-defense right away, and it took months for the cops to ask any questions. The perp in this case has already been arrested, so there's no need to demand his arrest. The differences are so many and so clear, but you diluted it right down to race baiting.
If you want to say that Zim killed Martin while trying to rob him, then it's a similar situation. This is not a controversial situation that brings bigger issues and laws into focus. There's no inkling of anything like "stand your ground" or self-defense as a concept in general. But no, that couldn't be it, it's all because of race. You're just acting like a white Al Sharpton now.