i think the way they look at something like this is "state of mind"
in this case his state of mind was "nigers were getting away with it" or something to that effect. If he was a Fox "newscaster" presenting some "factual" evidence and said that in a monotone voice, no one would have thought anything about it, but instead Z was a man with purpose and a gun. Whether his intention was to kill someone, i don't guess anyone but he will know, but what is known is, he stalked a person with the mindset that this niger will not get away with it, even after warned by police not pursue.
stupid people always seem to put themselves in "situations" which have unintended consequences. Does it mean we should allow stupid people to do whatever they want to do without responsibility for their actions? I think the basic question is, was Z defending himself in a life threatening situation? If, yes, then probably nothing more can be said about it, but if no, then he is certainly responsible for at least manslaughter up to some designation of murder.
