Don't read too much into it.
You're a cop. You're faced with a pregnant lady pointing a gun at you. What do you do?
Substitute pregnant lady with old man, young boy, whatever you want. They're not teaching cops to kill kids and pregnant ladies. They're teaching cops to stay alive by taking appropriate action (firing) on appropriate targets (armed subjects pointing a gun at YOU).
"It's ok that my husband was killed. The shooter was a young boy" See how silly that sounds?
Sgt Lumpy - n0eq