Per KTUU the victim retreated inside and armed himself. If the attacker hadn't fled, with the dog killed he and his sleeping mother would have been helpless otherwise. Being able to get to a weapon provided him the capability to stop any further assault.

I know you like your "clever" little "more guns" strawman, but the point of being armed for self-defense isn't that it is some sort of magic talisman, but rather it provides an option for defense which can and does save the lives of innocent victims of crime.