The author isnt claiming it's possible to win against a perfect opponent, but rather, all perfect play scenarios end in a draw. If both players either can't pla

The author isnt claiming it's possible to win against a perfect opponent, but rather, all perfect play scenarios end in a draw. If both players either can't play perfectly, or choose to play imperfectly, then it moves into unknown territory and either side can force a win. This does have to be mutual though, if only one side plays imperfectly, then the other can always force at least a draw. So if you know the other side is incapable of playing perfectly, it could be rational to deviate.