Actually, they do. If GZ had decided to randomly shoot someone and had randomly hit TM, I don't think the race baiters would have been particularly interested. The problem here is that Zimmerman and his supporters seem to think that it's proper to shoot a black person whose only offense is to try to beat a white person to death. Randomly shooting someone for no particular reason wouldn't be so bad, since it wouldn't be that much different from black-on-black killing. But the notion that battery of a white person should carry a risk of being shot is abominable.
Uh, Zimmerman is Latino, not white.