I agree. I hit a pedestrian a couple of years ago and some people are amazed at my “lack of compassion”. I look at it like this: It was 100% his fault (it really was) and therefore whether I hit him or some other car hit him is completely irrelevant. It is as if he was killed in an accident on the other side of the planet. It is not my responsibility and therefore not my concern, any more than any other accident of its type is my concern.
To be honest, I have no idea whether the guy lived or died, but I suspect he is still alive.
Same with this sort of thing. A criminal, while participating in criminal activity with the goal of bringing harm to others, is 100% responsible for what happens to him, assuming that what is done to him is not done in malice.
All that said, I have NO idea what long term emotional impact it would have on me if I chose to actually pull the trigger and kill another man, even if in defense of my own property.
It is at the very least a “bummer”. Sorry it happened.