Muntz isn’t actually much like Satan: he doesn’t tempt, at least not actively, and he doesn’t seem interested in being in charge. Rather, he is – among other things – a metonymy for those same childish dreams. Up close, being a globe trotting explorer turns out to be kind of creepy and lonely, with vaguely imperialist and explicitly anti-environmental undertones. There’s a certain amount of truth to this: a LOT of our childhood dreams are kind of messed up when you think of them hard enough. (Do kids still play Cowboys and Indians?) But the film hits it really, really hard. Particularly cartoonish is the row of trophies – goggles and helmets – that Muntz has collected from other would be explorers that he’s murdered over the years. That’s right – not only are your childhood dreams of adventure unachievable, they are lying in wait to kill you should you ever try.
The precise nature of the adventure doesn’t matter: in this case it’s wilderness exploration, but it could have been piracy on the high seas, or winning the international pie-eating championship, or pretty much anything else that involves actually going to exotic places and doing something exciting. Call this kind of activity extrinsic adventure, and know that Up considers it juvenile. In the badge pinning ceremony at the end, the other two kids are both up there for something absurdly badass… I don’t remember exactly what, but they’re getting their badges in cage fighting and enhanced interrogation techniques or something like that. And then there’s Russell standing up there getting his badge for assisting the elderly, and the implication is that he’s the only one who had a real adventure.
Russell’s adventure (which is presented as mature, and, in that it’s essentially about an emotional journey, intrinsic) could be seen as the act of helping another person. And I think this is what Fenzel is trying to say. But I see the name of the badge as a red herring, because by the end Carl can hardly be seen as some elderly person in need of assistance: he’s OBVIOUSLY Russell’s father figure. (Maybe they could have hit this point harder, but it would have required special equipment.) The only adventure worth having is not helping the elderly, but rather recreating the nuclear family unit. This is as true for Carl as it is for Russell: finally getting to Paradise Falls is an anticlimax, becoming a responsible father-figure is a happy ending. The pattern even works for Muntz, who can be seen as the Carl-that-might-have-been. (Note that the awesome sword-cane duel paints them as equal in decrepitude despite the fact that Muntz is easily thirty years older. Plus his first name is Charles, which is too close for coincidence.) If Carl Fredricksen hadn’t gotten sidetracked by that whole marriage thing, he too could have become a famous explorer… and wound up lonely, bitter, forgotten by the world, and spending his days talking to animals. Unless you buy into the film’s value system, it’s hard to understand why Muntz is a figure of pity. By any rational standard, he should be lauded as one of the great scientific minds of his era – as Russell points out, “It’s a talking dog!” – but we’re told in no uncertain terms that this too is a pale substitute for taking your kid to bingo night. And why is Muntz a villain? All he wants to do is capture a bird! He doesn’t even want to kill the thing, he just wants to tranq it and put it in a zoo. Why is that so bad? Because Muntz has bucked the system: he followed his dream of [anything other than child rearing]. This makes him bad. The fact that his dream involves splitting up another family unit, even an animal one? That makes him evil.