Sad but true.
Even though guns are more prevallent here, shooting someone in the back as they run away cannot be called defense.
I sympathize with his prediciment, but killing someone and expecting to get away with it doesn't cut it.
To take Genixias icecream scoop, it is not highly likely that he could have killed someone with his icecream scoop while they were running away, and if he did succeed in killing his burgler with the scoop it would have been a more clear cut murder.
We are back to acceptibilty again, should he go free because he used a gun to kill the burgler instead of a knife, or hanging, drowning, poison or set his pack of wild dogs on him.

The method of murder is irrelevant, the fact that it happened is very relevant.

Just like killing a fox by dogs or a chicken/rabbit by twisting its neck rather than shooting it.

I suppose only veggies can truly answer that last part