You are making assumptions where they are not ready to be made. A pokemon fan does not have to be a kid, especially in a country like Japan. Adults watch anime all the time there, including pokemon.
Also, satoshi never specifically asked not to be traced. He just disappeared and never replied any more. This can be due to many reasons, one being that he doens't want to be found, but he could also have died for instance (even though that is highly unlikely).
Still I have to disagree: few adults would watch Pokemon even in Japan, as it's definitely aimed for kids and young teenagers. I have a bunch of Japanese friends in their twenties (being myself in my twenties) and they indeed occasionally read mangas and probably watch anime (still I have to insist on the "occasionally" because Japan is a country where you'd easily get marginalized if you spend too much time on these), but I'd be surprised that they'd watch Pokemon. I can ask around if you want. I admit that I never did. But I'm pretty sure of the answer I'll get: Pokemon is for kids (and ok, nostalgic adults too, every now and then).
But I'm not pretending to hold the truth regarding the origin of the name Satoshi. I'm just going with my own assumption that if Satoshi is indeed a pseudonym, there's a possibility that it was chosen by a western pokemon fan born between 1985 and 1995. These are just my thoughts though. Don't sweat it: I have no evidence that what I'm saying is true. You could say I'm just talking out of my ass
![Cheesy](https://bitcointalk.org/Smileys/default/cheesy.gif)
. Especially if the guy is really Japanese but Satoshi is still a pseudonym, then chances would become really super slim that it would be because of Pokemon's creator, since he'd have a much more developed background regarding Japanese names.