There is no grey area when you deliberately, with planning, take another person's life. Grey is reserved for self defense, walked into house and found wife having sex with best friend, drunk as a skunk and killed a person driving home - not planned murder.
Yup I agree. He planned it, he went through with it, he's a murderer. Like I said, it's only a label. The larger question is not answered by what your point here.
The reason we have governments, the reason we have rule of law is because when government fails to, or can't act to protect it's citizens - we get what happened in New Orleans after Katrina. When we allow people to say "I'm the exception, I don't have to respect the law" - we get what happened in New Orleans after Katrina. We only have a very thin veneer over our barbaric nature. If we don't want to all have to fort up, if we don't all want to have to carry arms with us - we must require our government to impose justice and not impose justice ourselves.
So we have governments to have a rule of law to protect our citizens. Ok, where was the rule of law to protect his daughter? It was at least another day away. His daughter was dying, she was being killed by another murderer. She was helpless to save herself. He decided to save his daughter by murdering the drug dealer.
The rule of law protected nobody in this case. In this case, the rule of law gets to be applied after the fact and it was natural law and real ethics that guided the actions of the father, and thus protected society. And because the rule of law is applied after, it can't be used to protect but only be used to determine guilt and what punishment. Guilt is easy, it's just a matter of establishing if he did it, and with how much intent. But punishment is then applied by what basis? By the basis of observance of its own rules for the purpose of "protecting society", or for the purpose of recognizing that natural human ethics was the force being applied here?
If you observe the video, the courts actually applied the latter (natural human ethics) in the punishment - though they had to go through a veneer of law (not a "veneer of our barbaric nature", as you say) to get there. In the end, though they could not let him go completely free, they did what they could and reduced his sentence to the absolute minimum possible, even to the outrage of some in the community. I only wish they would have bended the law further and revoked his criminal record upon finishing his sentence.
I think you blindly applied understanding of the law in this case. As I explained it, it worked better and differently than you stated.
