I'm sorry but I have to not agree with this. And any one who's body needs to be hidden probably did it in what society would agree is an "immoral" way of executing it. I could imagine plenty of scenarios that can be played as a moral killing, but not the one you posed.
I just can't see how you're saying it doesn't make it immoral. Unless you're just saying if you take words and meanings out of the picture, and ways to express feelings, THEN there would be no such thing as immorality vs morality.
How can we separate "moral" from "immoral" killing? Killing is the death of another creature, large or small. How can we possibly be the judge of whether something is moral or immoral to begin with? What gives us the power to determine levels of morality in the face of death?
Scenario 1: Killing an animal out of pity.
Animal one has been injured after being hit by car. Person one determines it is better to kill the animal.
Scenario 2: Killing a human out of pity.
Similar scenario.
As people in a worldwide society, it would more likely be determined that killing the animal out of pity is
less immoral than killing the human. Deliberations would be made between panels of humans to separate the cost and potential risks of saving the human. And if the human was killed before the deliberations came to a close, a lawsuit might ensue.
However, this is the same scenario. The experiment is stable except for what is being hit. How can we say that the death of the human is more immoral than the death of the animal? They are both
very important members of our ecosystem, society and the ever changing lives we live. Yet, the death of the human is more immoral.
Therefore, my inner conclusion on the face of morality due to death and killing is morality is judged by those who think of some beings as higher than others.