This is another question I have never seen considered by a philosopher, but it is important in psychoanalysis.
Death may not meaningfully deprive the dead person of anything, but it clearly deprives those most closely involved with that person of whatever they are getting out of those relationships. So considering death is averse to the person being killed because that person holds obligation personally, including the ambiguous obligation that simply being in relationship entails.
Existential forms of psychoanalysis that focus on identity and motivation therefore always impute loss to death, because one affect how the requirements of your identity play out or pursue your motivations after that point. To the point that your social identity is you, it is threatened by death, and, therefore, you are. Your bodily instincts know that, even if your conscious mind has decided otherwise.
From that point of view, killing is an assault not so much on the dying person in his current state, but upon his past ability to plan his life (the ways in which that has been rendered flawed, incomplete or damaging when it could have been more rational) and upon those who might have been affected by those plans.
This includes (if you believe in them) the transpersonal and transferential motives that might have been advanced by his existence. (For Kleinians, e.g. the loss of a parent removes a symbolic real-object link, and any attachments to the images of that parent then must be resolved by less efficient means.)
Only a person free from the conflation of self and identity, outside the constraints of real obligation, and neutral toward all transpersonal goals, can, then choose death without loss. Those are relatively few. And even toward them, forcing the issue, by threatening death, or otherwise causing it to be considered as an option, is always destructive, even when the actual killing might not be. The very detachment and equanimity that would make them able to accept death is threatened by instinctive reactions over which no human truly has control.
Besides that, the transpersonal and transferential goals are still not those of the person making the decision, so they cannot be ruled out by his choice.
Thus, from a broad enough psychodynamic perspective, death is a comparative harm both to the individual and to others, in imaginal and symbolic terms, even though there is not necessarily anything in the real world that is being taken away from the deceased.