I think its not a double-bluff. Its a triple-bluff.
He says he makes some spacegame - but in a way we dont believe him. (Bluff 1) | Now we think hes Bluffing the Bluff, since it is so obvious. And we start to think that he could really make that spacegame (Bluff 2) | But in reality he is just bluffing the bluff, what would be (Bluff 3).
Easy, huh? ;)