Jaime: I'd say that what he's describing is simply the phenomenon called nostalgia.
I'm not 100% sure. There's a sense of loss in nostalgia. I'm nostalgic of things I've lost and won't feel again. He seems to be able to restore all these impressions, and reactualise them. This is different from me being nostalgic of my uncritical views and childlike enthousiasm for a random Terence Hill & Bud Spencer fight scene, for instance. Or the magic of some novelty. Or the powerfulness of the exagerate love I've felt for some human lady. Or the enthousiasm for singers who evolved badly enough to give an annoying taste to their former songs. If I managed to enjoy these songs as fully, it would be a present pleasure. I'd be driven by the direct enjoyment of the thingies, not by the moments they indirectly remind me. Although both aspects can sometimes be combined.
Anyway that's one thing. For the rest, I disagree. While I have reservations about encyclopedic nerdism when it's an accumulation of fiction knowledge at the expense of the rest (but, again, aren't folklorists, mythology experts, and some anthropologists, just "anachronical nerds", learning teaching and analysing corpuses of popular fiction ?), I'm not certain you can read it as a "refusal to outgrow" some pleasures. First of all because it's never general, it's always selective (everybody outgrows a lot of things), so deciding which ones are obligatory and which ones are optional sounds a tad arbitrary, and driven by personal preferences, or worse, personal exposures. I personnaly find adult references to star trek, dragonball, disney, dc/marvel or transformers much more morbid and puerile than references to james bond, the persuaders, tintin or space 1999. Because I liked the latters, and I disliked the formers. And being faithful to "my" universe is fine, being faithful to "their" universe is obviously totally retarded. Mine is of an absolute superb quality (proof is : it's mine). See what I mean ? Call it the Prince Valiant syndrome (sooo lame compared to Johan & Pirlouit, hah).
People are idiots because they don't outgrow the idiocies they used to wrongly enjoy. I don't need to outgrow mine, their quality is totally objective. To my eyes.
And some of them are double idiots. They're so dumb that they claim to "outgrow" MY stuff. They SO can't appreciate genuine quality, when it's done for children !
... So, what annoys me, is less people who say "omg I liked this so much, I don't care how lame it is, I enjoyed it and still enjoy it under the same angle" than people who do the same, but with guilt, and try to justify it ("hey, the a-team was so DEEP, you just don't get it, man"). As a kid, I didn't like people trying to sound adults. As an adult, I like them even less. I don't believe in adults. Especially those who "outgrow" superman to go praise the last Daniel Craig james bond, or whatever equivalent, just as childish, but designed to make them feel more "adult". I'm totally behind Roger Moore when he claims that his childish version of Bond is more mature than the so-called serious, pseudo-realistic action thrillers of today. There is, quite often, an hypocrisy, and mere (age class) identity issue behind these. "WHAT, they made Aliens versus Predator versus the Avengers PG-13!? They made it for KIDS ? I'm a GROWN UP, I want to see a REAL ADULT superhero space monster story !"
I don't think it's really about "refusing" or "accepting" to outgrow things. There are things you appreciate less with time, for good and bad, related and unrelated, reasons. There are also things you are not allowed to appreciate anymore (until you have kids and can use them for a socially acceptable co-consumption of these things). These things differ a bit from individual to individual, just like taste evolutions differ (we're exposed to different elements of comparison, and the old things meant different things for us to start with). And the pressure to distancize oneself from childish-labelled stuff is also lived differently for various individuals, in various communities (Tex Avery, or Tintin, can be a validated adult interest in some subculture, Superman and Batman can be in another, etc). Essentialising it under one universal label of psychological/biological cognitive development is very restrictive, and probably quite biased in its content.
There can be discussions about objective qualities (on various levels) of productions for kids. I think it's very distinct from discussion of what supposedly has to be outgrown or not. After all, still appreciating something later, but under a completely different perspective, is also "outgrowing" it, and is not exactly what we talk about. And also, accusing adults to be dumb enough to not "outgrow" some things is, in my opinion, rather harsh towards the adults who produces these very things, and considered that they were worthy enough for the public. If a man in his prime still appreciates a kid/teen show/game/book,and is judged as retarded for that, what's to say about the people in their prime who have put their heart into making them ?