It seems these people did prepare properly for such a trip.
Yea, sometimes the unexpected happens at sea. It could have been one of the parents just as easily and the same response given. I've seen parents do far worse and far more dangerous. I like close to the Smokey Mountains. I was hiking about 18 years ago on a trail that was 5 miles up to the top of the mountain in very dense foliage. As I was coming down late that afternoon a woman came running up the trail and asked me if I had been to the top. I said yes. She said did you see two boys? I said no how old are they? She said 7 & 10 I think it was they had left that morning for the field at the top of the mountain. A man on horseback came by I talked to him and told him what was going on and he took off for the top. I took her to the Ranger Station.
Those two boys were in far more real danger than the parents and kids in that boat. When I was about 13 I was hiking with my dad and a family friend in back country. A 7 year old boy had disappeared on that same trail the day before. He went ahead of his parents and from what they think tried to take a short cut. He was never found. The two boys of the Mom I met were lucky they were located before dark. The mom did not realize the danger the boys were in. Adults get lost in those mountains and panic kills. So does hypothermia even in the summer.
The kids on the boat with their parents in this article are safe enough it's just illness happened. Kids live in areas everyday here in the USA with far greater dangers around them like persons who live in say southern Louisiana.