Well, I wouldn't call that cheating, since the odds are still the same. In a normal game of RPS, ignoring any psychological "tells" or the like that might weight the process, it's a straight up 33% chance of three results - Win, Lose, or Draw. In D:OS, assuming there aren't any "hidden modifiers" behind the scenes, they just remove the Draw result - making it a 50% chance to Win or Lose.
Like I said above, it's more of a coin toss than a game of RPS. Personally, I just click the same thing over and over again, and inevitably get something like 2 wins and 2 losses before winning the argument overall (since I stack Charisma). It might be kind of fun in Co-op, for settling player-to-player disagreements, but in SP it's definitely a waste of time.
