Partially guilty of not keeping up on this thread.
In that posting, the 'preferred' part was tongue-in-cheek, referring back to a previous YL Gull thread. Maybe should have put a smiley . . .
Although I think it an argument which has 'some' credence.
But probably not if
a) the animal has been caught already, taken into custody.
b) its a bird like a Kestrel with an injured wing.
etc
Examples where it could be appropriate;
a) a common pest which will provide food for someone else in the food chain.
b) mortally injured reptiles etc - don't know how to despatch them.
c) mortally injured creatures which are about to be food for another creature.
d) creatures which are apparently going to 'slip away' anyway. (eg baby mice as mentioned, ill/unconscious creatures etc)
Maybe I'm just particularly cruel and heartless!
On the other hand, happy to be wrong on some (all) of these, as I am in an obvious minority, and no vegan buddhists/animal spirit believers etc have come wading in with their arguments why something should not be despatched.