You infer this is a performance cat and more susceptible to capsize. These performance boats, mono or multi, are closer to the edge. If the capsize was proven to be caused by the tightly sheeted sails (not easy to do), then it would be nice to have the ability to ease sheets from a control, inside.
Obviously this was a fluke condition that would have taken any boat by surprise. The roar they heard was obviously severe wind approaching. But I guess unlike a typical gust or gale, this came from an upper angle. It may have happened with the sheets loose. Bizarre!