I don’t remember the last double diversion I noticed, it’s rare and unfortunate for all the passengers on the flight. But when you’ve got a medical emergency that takes precedence, and on ultra long haul flights you can easily face crew limits which are regulations in place for safety. So an airline makes the best decision possible when faced with tough choices, and this one is tough to second guess.
Ultimately an airline-paid hotel room in Hawaii is a better place to spend the night than inside the terminal in Shanghai.