What a shame this story is. If the slots had a malfunction it's none of the gamblers' business. The casino is responsible for it. And since the machine was disponible for playing and the gambler has won, it's their duty to pay the prize the machine displays. I think it's funny this kind of malfunction never happens for the other side. When a gambler loses there are no malfunctions with machines. It's purely lack of luck.
Another advantage for crypto casinos: provably fair feature, so you aren't going to hear your payment is going to be denied because the machines weren't working properly.