What Silman describes here is a textbook scenario of what you should be aiming for when fighting an isolani. If you reach the diagram position, you will collect the pawn and win the game.
But of course, this is not the only way to win a chess game. It should be considered as guidelines: exchanging minor pieces is good because it reduces the value of the outpost on e5, keeping at least one rook is good because it can attack and pin the isolani, and the opponent's rook is clumsy at defending, etc.
Also, it is a warning that the camp with the isolani must do something specific, building an attack or changing the pawn structure, because if the game follows a quiet flow with simple exchanges, they might find themselves trapped in this losing scenario.