Common sense in a sinkhole

The cave rescue was at the centre of this episode and sadly the writers' notion of common sense fell into a sinkhole, too. How can one of the people trapped in the cave develop a lung infection within half a day (without being exposed to any extreme conditions)? Even at the risk of hypothermia, wouldn't diving out be better than being drowned by rising water levels. This decision made absolutely no sense at all!Fortunately the actors made up for these obivous flaws in the script. DingDing playing the corporate game was another thing to admire in this episode.