Dr Who - Morality Quiz

A casual email chain with MyMateMatt started off this thought : should we not be questioning more closely the human/alien interactions depicted on supposedly responsible programmes like Dr Who ? An example taken from a recent philosophical exchange -

MATT :
"... one moment they were bunkered down, armed to the teeth and succesfully taking out the scarecrows in satisfying quantities and the next they were all running away like big girls. I'd have shot the little girl - her balloon was getting on my **** anyway - after all she did vaporise the headmaster"
JC:
Ah, well now - if only alien extermination was that simple, eh ? It's the old chestnut :
"Am I entitled to waste a small child (who has effectively sacrificed its claim to human rights by hosting an alien lifeform) once it has vaporised a leading education representative , or must I tolerate the irritation of its balloon-brandishing until a majority of the school establishment have been dispatched ?"
Always a loaded question.
Personally, I was more worried about WHY a hail of bullets passing through straw should be fatal to animated scarecrows which lacked any vital organs or conventional blood supply. If only they would explain these things, eh ?

Any views ?