Did he kill the lion to eat it? No. I don't agree with killing chickens for fun either. If he had needed to eat it, that would be more forgivable. So, if you had to kill a chicken or an endangered animal, which would you kill?
And herein lies the problem with the whole I-care-for-A-but-not-B-because-X school of thought
So we should only extend kindness to animals when they are endangered and/ or they don't become our food?
By that way of thinking it would have been okay to slaughter (and eat) whales 50 years ago.
At the end of the day
slaughtering an animal is still slaughtering an animal; you think a pig gives a fuck whether you are going to eat it or not after it has died. I think that's probably the last thing on its mind.
"Oh but I killed it to survive brah, I
needed it for food". Again, this is a problem because you can still actually survive without having to kill something, you just use it (your survival) as a justification for your actions.
I liked your little scenario though, it makes me remember all the times in my life that I have been similar situations like that. Almost like every time I get stuck on a deserted island...