It's because he wants all the attention on himself.
Notice how he only begins to speak when some 'leaks' start being talked about. How he has a tendency to hold back info, use vague descriptions, and to try to falsify other leaks. Like how 'any leak without Isabelle and Simon is a lie!' and 'I know who the next Pokemon is, but it isn't ___!' It sounds to me that he wants all the attention on himself, and I think it's only a matter of time before his lust for attention causes him to slip up.
If he knew, why not say it, since he's already said Simon and Isabelle? If he knew of Snake and no Wii U cuts, why not mention that everyone's back? If he knew of the E3 build, he would've known of Snake and Ridley, but how could he have known that there were no cuts? I don't put much into him guessing Ridley at E3, because I guessed the same thing would happen. No cuts from Smash 4 wasn't a hard guess, either. Snake coming back was a risky call, but was never impossible. And if you're going to guess Snake, Simon Belmont isn't far behind. It seems to me that he managed to guess some stuff right, and is trying to keep this going as long as possible.
Now it sounds like he may be jumping to conclusions based off things he's been told to bring back the spotlight, or he's making things up to spark debate.