No that is not a deterrent at all and does not make sense. Already shooting somebody on sight gives you ample time to loot his corpse and be very well away from there, not considering the time it takes for him to return to the exact place, navigate, locate you and find a weapon to kill you. The respawn delay will make people who are going to consider KOS execution think twice about the possibilty of being bested in the fight and having to suffer the consequence of long respawn.