"Tricking an opponent into thinking it has metaphorically thrown rock" extrapolated into a poker example would be betting larger/smaller, calling more/less, folding more/less than is optimal in a given scenario in the hope that your opponent makes a (bigger) mistake. You're simply hoping he makes more errors than you, the AI instead choses to just make zero mistakes and let the opponents do the rest. You can see this in action for yourself in Heads up limit holdem by playing Cepheus (http://poker-play.srv.ualberta.ca)
I agree that would not happen if two equilibrium-seeking computers played each other. Since the human strategy is unknown, it is possible that equilibrium may not exist or be optimal. Even if it's two computers, if one of the computers has the possibility of choosing a non-equilibrium strategy, then again the optimal strategy may not be to seek equilibrium.
Poker isn't about equilibrium, it's about misdirection and exploitation. When the table gets cold, you liven it up by convincing everyone to do a round of straddle.