Not sure if it's "couldn't" or just didn't want to, if they really made little money on the game.
But, there seems like there's more to this story. I haven't played the game... but having a popular free-to-download game and making money on consumables is the new App Store model.
So seems if it was a very popular pirated game, they could easily make money promoting it to the broad free-to-download audience and make money on in app purchases. I'm guessing the game will come back retuned as a free-to-play game. (looks like it already had IAP, not sure how effective it was).