Hades isn't asking for a game exactly as he wants. All he wants is a sequel true to the spirit of Fallout.
That by definition requires it to retain certain qualities. Otherwise it's just Bethesda's take on a post nuclear RPG - but not FO.
He's also saying that if Fallout 3 turns out to be a great game, but has nothing to do in terms of design with Fallout 1 and 2, then he will never touch the game.
And that's silly.