I realize that you're probably making this post more to make a point about ideology, and not as much about the story itself, so I won't bother commenting on the story, which is plainly a tragedy perpetrated by some seriously addled people. Which has very little to do with what rights people should and shouldn't have, because no set of rules can ever give people freedom and safety yet still cover the worthless fucking nutjob contingency.
However, my overall philosophy leans in the other direction from this. At least sort of. The two don't entirely correlate because this situation is somewhat different, but I think the principle of other people who are forced to put up with the bullshit of others in their community is too often overlooked. This country is far too lenient with citizens who think they own the planet and have no respect or concern for anyone other than their own immediate circles. This is a gigantic problem amongst several specific ethnic communities which made it impossible for me to live happily where I lived before, which is why I moved. Much of what the people who still live there, regardless of ethnicity, are continuously forced to endure should be illegal but isn't, and even the points which are illegal aren't enforced. I know because I tried to get them enforced and failed.
Though it's funny, because my initial sentence about citizens lacking respect for others could just as easily apply to these worthless scumbags who shot the kid.