There was a previous post about this topic that actually linked to the paper, which I think you'll be happier with.
In particular, what the extortionate strategy does is the following: if player 2 accepts that player 1 will play the extortionate strategy, and there's nothing to be done about that, then there is a linear relation between their scores, and he can only maximize his score by giving an even higher score to player 1. In particular, if player 2 plays TFT (which is also an extortionate strategy, in a degenerate sense, with extortion factor 1) then the two players eventually end up in the (Defect, Defect) state, and get 0 points per turn, which satisfies both relations.
How does this actually get implemented in code?
Less Wrong had a Prisoner's Dilemma contest some time back, whose results I've forgotten. Perhaps it should be rerun with William H. Press & Freeman Dyson's proposed extortionate strategies.
I hope Pinker gives a response at Edge.org, since P.D played a significant role his book "The Better Angels of Our Nature" as a source of morality embedded in the nature of logic/reality.
Hat-tip to Marginal Revolution.