It's my opinion that if a white person had those photos on their phone, it would count negatively against a claimed peaceful character as well.

Unfortunately whether Martin was peaceful or not is absolutely not irrelevant. An important part of a trial like this is character construction / deconstruction by the prosecution and defense.

I suggest that it is. Let's agree you are a peaceful person; now imagine the following sequence of events, which I've tried to present in the most neutral terms possible.

a. You are walking along the street, at night, talking to someone on the phone.

b. You notice me following you, driving my truck at walking pace, for at least a full minute - half a block, probably.

c. You pause and stare at me. I stare back. You see I'm also on the phone.

d. You approach my vehicle a bit more closely.

e. Something makes you decide to turn and begin running away from me.

f. You hear me get out of my truck and start running after you.

Now, just answer me one question: how would you describe your situation at this point?

Should their photos be allowed into evidence? I.e. should the jury be allowed to consider: 1) their support for a hardline right-wing sheriff; and/or 2) their membership in an armed anti-immigrant organization? Or would that bias the jury?

I get that you're trying to pose the question of whether the homicide victim was also an aggressor, but if so we need to include the context that the person in question was fleeing the defendant when the alleged aggression took place.

If I chase you down the street for no good reason, and you turn around and punch me in the nose, who's at fault?

It has absolutely nothing to do with Martin being black or white or any other color, nobody said the missing information is relevant because Martin was black (and that fact was obvious from the start, so nobody in his right mind could claim there's some new information there) - the claim was that the information was relevant because Martin allegedly had closer relation to violence and firearms that was previously known. Nobody ever claimed that Martin was aggressive because he was black. The racism charge is pure bullshit. It is a fallacy to claim that it is always racist to say some particular black man is violent, because it "implies the stereotype". Well, some people are violent, and some black people are too - and the question was not whether Martin was black and thus violent (it is obvious he's black but that says nothing of him being violent) but whether Martin was violent regardless of him being black. And the data in the phone was relevant to that. Exactly because it is not imply that Martin was violent just from him being black, we need some evidence beyond that to figure out if he was - and the phone data is that evidence.

Are you arguing that the judge was wrong not to let evidence of Zimmerman's violent past be introduced?