Ryan Cheyney argues that when an innocent Victim defends himself against an Aggressor by killing the Aggressor, he can justify his killing the Aggressor by saying he was not responsible for killing the Aggressor. Please bear in mind Victim has good reason to believe Aggressor is out to kill Victim and that only by killing Aggressor can Victim hope to live. Crucially, it follows from the fact that Victim is not responsible for the scenario he has found himself in that he is not responsible for his killing Aggressor.
I do not follow the step from the Victim not being responsible for being in the situation that he has found himself in to the idea that he is not responsible for the action he decides to take, whether that is killing Aggressor or allowing Aggressor to kill him.
One reason why I fail to see a connection is that ordinary language would describe the situation as follows: the Victim chooses to kill Aggressor. It seems to me choice and responsibility are intertwined. If you have a genuine choice, which the Victim seems to have, you automatically are responsible for the choice you make.
Let me explain my point by way of analogy. Suppose you are teleported by an evil scientist to a bar. No one would suggest that by being in the bar makes you responsible for being in the bar. Nevertheless, you can either stay or leave. This choice is not something the scientist who teleported you to the bar is responsible for.
In the same way that the scientist is not responsible for you being at the bar the Aggressor is not responsible for you killing him.
So, can responsibility or the lack thereof justify self-defence?