I worked for 5 years, and part of my job was inspecting, maintaining, and making emergency repairs on underwater hydraulic and electrical systems aside from the structural work. Running out of air in recreational diving is one thing, but in the tight, dark spaces of a cave, or under a moving piece of machinery it is another.
The one guy, Huotarinen, in the article died while trying to switch mouthpieces, and he was an experienced cave diver, not recreational diver.
He died at 130m stuck in a tight restriction, breathing a rebreather and after many attempts on freeing him self he died when he tried to switch to bailout gas. The reason why he didn't manage to do such an easy task is most likely related to the fact that he had been breathing heavily from the rebreather and because of that most likely suffered from hypercapnia (to much Co2)...
The one guy, Huotarinen, in the article died while trying to switch mouthpieces, and he was an experienced cave diver, not recreational diver.