Why would someone want to make up a story like this? It's not as if he's claiming to be the prodigy. Surely someone would not write such a long article for the sake of making up some 8 year old who possesses natural chess talent, as is the case for a lot of young children...This story does not seem unique to me. The only reason I would have for believing this story is false is that "Adam" played like a textbook for the majority of that game. However, the one book that he supposedly learned from was by Kasparov, which suggests there is a ton of theory on the Sicilian Najdorf. So it actually makes sense that "Adam" was able to replicate all of the theory in his own game. I believe anyone accusing this guy of lying is either a troll or perhaps jealous of a stronger chess player who is indeed younger.
You don't understand chess or human nature. (Or you're a troll yourself.)
Nevertheless, if you aren't a troll but simply an ignorant person, here you go:
http://en.wikipedia.org/wiki/M%C3%BCnchausen_by_Internet
http://en.wikipedia.org/wiki/Pseudologia_fantastica
there is roughly a 1 in 216,272 chance of someone with a 1200 rating beating someone with a 3334 rating.
This might be applicable in human terms, since after 216,000 odd games any human will probably make a blunder. However a computer never will, the probability of a 1200 human beating Houdini is 0, absolutely 0 no way around it.
The computers blunderless, consistent play is part of why they have the rating they do. You don't get to say "Well, his rating is 2400, but he is very consistent, so he acutally should be rated 2800".