Law is trying to view the facts in a way favorable to your side, and then convincing a jury. Since you are dealing with people, who do things different from the law, ignore, it, jury nullification, etc. the only thing absolute is that there are no absolutes.
Making blanket statements about what would have happened in any other state is absurd. Making statements about 'facts', when so much of the 'facts' were part of the problem: that being credibility of the shooter.
Why aren't they trying him again?
If I'm a prosecutor, and I have been an assistant to more then one, I look at what, with the appellate ruling, is likely to come into evidence for the next trial. Given a proper jury instruction, any witness testimony to K's violent history, and his dogs violent history, and I have to think there is a possibility
that murder, or second degree murder are unlikely convictions. Everyone in that jury pool is going to know that K was a rapist-kidnapper and mentally disturbed. Fish's gut told him correctly that it was likely, given the guys history, that he probably intended to do great physical harm, or kill.
If it wasn't justifed, then it's going to be manslaughter, or some lesser charge. Fish has already lost 10 years in prison, and, it's unlikely the manslaughter conviction would merit more then that.
As a DA hat, I would say let it go, I really won the trial, and move on.
The DA did win. The judges' error on jury instructions was the real reversible issue in the trial, and his failure to instruct the jury on their question.