That's not an entirely fair assessment, at least in this case. He ported a popular Web game with about 3 hours of content to an iOS game. He made about $700,000

That's not an entirely fair assessment, at least in this case. He ported a popular Web game with about 3 hours of content to an iOS game. He made about $700,000 gross on that. He then followed up with a few partial attempts at similar games that were either a) built to be exceptionally hard (The Ensign) or b) unfinished and barely playable (A Noble Circle). I'd say the unsustainable part for him is his entire (lack of) business plan. It shows very little other than the fact that very little sticks when you throw random things at a wall.