...you need to think from the thief's point of view.
In a lot of the posts here, especially related to the aging of lions in TLK, I've noticed something very important and I think that all this time, a lot of us (myself included) have been thinking about things all wrong while trying to figure things out about the Lion King world and what it contains, whether that be characters or the TLK world itself and its realities.
The creators of TLK studied lions before making the films, then they went to the studios and created a fictitious world, with fictitious characters, with fictitious realities specific to that world. When we're trying to figure out whether or not something happened, or whether it happened one way or another, we need to think in the terms of that fictitious world that is TLK, and not the realities of the real world. If the lions age a certain way in the TLK world, that's what we need to refer to when discussing TLK character aging, not the way real-life lions age. Same goes for everything else that is TLK. We need to think in the terms and realities of the fictitious world TLK takes place and resides in. That means the books too, and it means keeping controversial characters such as Kopa and Mheetu in mind at all times, not just when they support our arguments and ignoring them when they hurt our arguments. If something that is canon (or merely official, for all you book canon haters) hurts your argument, maybe your argument is flawed and you should re-evaluate it. I know that's happened to me before.
So let's stop trying to force our own known realities, such as the way lions age, onto a fictitious world in which they don't apply, and think from a TLK world point of view. After all, you don't get anywhere trying to solve a math problem with lessons learned in Spanish class.