Justification varies with locality
Two points: While we're mainly concerned with face-to-face encounters with criminals, deadly force could also be justified to prevent the arson of an occupied dwelling, rape or kidnapping. I don't know the laws where this incident occurred but I too would have used deadly force to prevent my child or grandchild from being snatched.
When bad guys occasionally started showing up for work wearing bullet resistant vests, we trained the troops to shoot for the pelvic region, not the legs, if they suspected their adversary was wearing body armor. The pelvic region is filled with good stuff and is easier to hit than the head.
Int'l Assoc. of Law Enforcement Firearms Instructors