That is weird to me. I can think of two things if the breaks malfunction.
1. Turn off the engines, let gravity do the work (though it could take a while for the swaying to stop depending on the bearing system they use and that is possibly what they did if they couldn't fix the breaks)
2. Throw the motors into reverse since those ships are driven by tires like a ferris wheel (though this could severely damage the motors)
I can imagine being stuck on a ship for 15 minutes like that would be sickening, but I think people are overstating how terrifying of an experience this was to be on a pirate ship for 15 minutes.
Unless the park didn't do #1 and the ship actually was in full swing for 15 whole minutes. Which would mean the ride operators panicked and didn;t know what to do.
All in all it is kinda a comical event if you disregard the human suffering involved, which I am not saying one should nor am I condoning chuckling softly after you read the article.