Trample One's Rights to Protect Another's?

The facts are as follows according to CBS News: Joe Horn of Pasadena, TX saw a neighbors house being robbed. He called 911, but they took too long to respond, so he went out his house with his shotgun and shot the two alleged thieves before they could escape. (To see the transcript of the 911 call, click here)
Texas gun laws have changed since September 1st, so I'll leave the judgment of his actions to the courts. It's a shame the crowd in this video didn't see things that way. It's one thing to advocate for gun rights or home defense, but the mob mentality seems incapable of being swayed to anything less than the most offensive and primitive of motives. No one held signs that said "Support the 'castle doctrine' bill" or anything similar (and hopefully more clever). Instead, we were treated to an angry group of (all white, notably) people yelling "USA" and holding signs that said "Go Home".
Not to be facetious, but why would you chant "USA" to support any cause related to this? Was the dubbed "black-supremacist" group the New Black Panther Party chanting some other country's initials? And proclaiming USA at a group of black people while holding signs that say "Go Home" may send a different message than you(hopefully) intended. I find it ironic that a group claiming to support one American's right to bare arms would impede on another American's right to assemble, while assembling in a less than peaceful way themselves.

And how many young faces did you count in the crowd?

This is my country, they say.
Moments like this, however, surely don't make me feel that way. It is unfathomable to think things would have turned out the same way if skin colors were reversed at any time. Had a black man shot two white men for robbing his neighbors house, I get the feeling the legal ambiguities would disappear a lot faster, since he clearly wasn't at home or wasn't being robbed himself. If he was white, and a crowd of his supporters were accosted in the streets by a mob of angry black people, how does history teach us the police would respond? How would the media respond? We have a lot of work do to in the country regarding race relations. The people who advocate for peace(myself included) remain silent too often, while the most destructive and divisive of racist are training their children to carry on the tradition, the same way they were taught. This year, let's finally stop sitting by idle, and start to take action. All it takes for evil to prevail is for good men to do nothing. Do something.