Security ... think about it!
Had one of the first women who Davis attacked shot him in self defense, it is very likely that the subsequent victims would never have been through the terrible experience of having an intruder violate the sanctity of their homes and their bodies. If Davis had been killed, he certainly would not have been able to go on and victimize another person. Had he merely been shot and wounded, Davis very well could have been swiftly captured by police when he sought medical attention, instead of spending the next few years raping more women.