The end of the story also stood out to me with all the advice on what to do in preparing for a cruise if you have an existing medical condition. Bring your medical records, dosages for all prescriptions, any drug allergies and have proper travel insurance that will cover evac if needed. It points out that all forms of coverage are not the same. I don't know if any of this would have prevented this tragedy as it does appear that mis-diagnosis by the ship medical team may have contributed. The symptoms mirrored noro-virus which is more common than the long term conditions this man obviously had. Whether the staff knew is not obvious in the story. If they didn't, they should have been informed. The wife certainly knew and should have suspected, as it appears she did, that something far more serious than a virus was possible as his condition deteriorated. I agree that if there were such concerns, seeking medical care at a hospital would have been the prudent thing to do. You never know the reasons why people don't do the thing that in hind sight becomes obvious. Perhaps they thought he'd get better and didn't want to go to the expense and trouble of hospitalization and hotels, flights home, etc. Proper insurance coverage would have relieved the anxiety about the extra cost of medical care, flights, evac if needed or wanted. I don't know if these concerns are the reason for inaction to more pro-actively resolve this but its possible.
Incorrect diagnosis is possible at a hospital as well as on a ship. At least in a hospital you won't be quarantined to your cabin, where care and equipment is possibly a long way from you.
This brings back to mind the infant that was ill and referred to a hospital only to have the ship and staff again criticized for "Kicking a family off a ship". They incurred expenses for passports, flights, medical care and missed the rest of their cruise. The outcome was quite different, the infant is now fine. This gentleman could have benefitted from being "Kicked off the ship" and sent to a hospital for proper care. Either way, the cruise line will be the target of criticism. If they refer you to a hospital, they cost you the rest of your cruise and add'l expenses. If they keep you onboard and something tragic happens, they were lax in their judgement. The outcome seems to dictate how and to what degree they'll come under fire.