Who instigated the situation in the Martin case isn't clear according to the evidence and testimony.
Fear for one's life isn't justification, a reasonable belief that someone is going to severely injure or kill you if their actions continue is justification. You say someone's belief is wrong using the "reasonable person" test and the evidence and witness testimony. The shooter in this case stated that he didn't believe his life was in danger, according to the story and the evidence and witness statement shown so far don't appear to support a claim of self defense.
In one case all the evidence demonstrated that the shooter was beaten while on the ground and may have had reasonable justification in shooting the other man. In the other case the statements and evidence that we have seen show a man with no legal justification shooting another man. It's likely that for some race plays a part in their opinion but if nobody knew the races of the men involved, many of the opinions would be the same.
You left out the fourth group that believes the laws are fine how they are but the evidence and testimony didn't prove Zimmerman guilty of murder or manslaughter beyond a reasonable doubt. We're waiting to see more evidence and testimony on this case but likely never will because there is no major public outcry regarding this case.
Sent from my Huawei-U8665 using MonsterAquariaNetwork App
Pretty sure that fourth group is just about the same as the third group. Once his lawyer gets a hold of him and into court he will say he felt his life was in danger, self defense, SYG what ever he has to say to be found not guilty.