You're in a desert walking along in the sand when all of the sudden you look down, and you see a tortoise, it's crawling toward you. You reach down, you flip the tortoise over on its back. The tortoise lays on its back, its belly baking in the hot sun, beating its legs trying to turn itself over, but it can't, not without your help. But you're not helping. Why is that?
The answer is simple. I'm not helping the tortoise because I intend to kill and eat it. Otherwise, I would not have flipped it in the first place.
If you're gonna kill it then kill it. Don't revel in its suffering. That's the stuff serial killers are made of.
It's a purely hypothetical question, so I have to imagine a scenario in which I would do something like that. Ordinarily, obviously, I would never harm a tortoise. I would also never be walking alone in the desert in the first place, so I have to wonder how I got there. The first thing to come to mind is that I must have been in a plane crash, and that nobody would know where to look, as I otherwise would have simply made camp and waited for help to arrive. This implies that I would need to use my survival skills to make it to safety. Which means that in order to eat, I'd have to kill things I ordinarily would not. That's where the tortoise comes in. I certainly wouldn't want it escaping while I dispatch it, so I would flip it over on its back while I drew my knife, and watch it for a few moments while I decide the best way to kill it as cleanly and painlessly as possible. Most likely, I'd simply remove the head.
Goodbye, little hypothetical tortoise. Also, COME ON, BUBBLES! Don't just let her get away with it! Tear that *squee!*'s weird metal head off!