And all that solely to spare the attacker the consequences of his choices. I'd rather err on the side of the victim here - they didn't choose to be in that position, they were placed in it by actions of the attacker.
Note that this all only applies when the person defending themselves is in a position where they reasonably believe that they're in danger. It's generally not legal to defend your property with lethal force in US, if you are not endangered yourself; the sole exception is Texas.
A more important question is why. We're discussing a situation with a premise that we have already firmly established that the victim was violently attacked, or had a credible threat of the same (if we haven't, then it's not self-defense by legal definition). At that point, why would you accommodate the attacker at the expense of the victim, so long as victim remains threatened (again, if they're no longer threatened, then it's legally not self-defense)?
I often hear truisms such as "every life is valuable", but that goes both ways, and there's no way to avoid judging the relative value of victim's life versus the attacker's in this situation. Since it was attacker's choices that create this contradiction in the first place, I believe that they're fully responsible for it - i.e. the victim has no obligations whatsoever to think about the attacker's safety, only about their own and that of bystanders. Which means removing the threat by the most efficient way possible, rather than the most humane towards the attacker. Once attacker is no longer a threat, then considerations of the value of their life etc are back in force, because it's no longer at the expense of danger to someone else.
Safer for you, right then (unless you, you know, actually need that money, for food). Unsafe for all of their future victims, whom you have just chosen not to help. This is true for the same reason that evolution and game-ification works... Applying positive feedback to an action increases the likelihood of that action being performed again. By giving in, you choose not to stop them, and communicate to them that what they are doing is okay.
Sometimes "safely escaping" is not something you have the time or option to even consider.
It's simply about the human right to defend one's own life.
Report the item as stolen and move on with your life.