Again, if your aircraft is grounded you would consider yourself stranded at an airport until you could schedule and board alternate means of travel. Even though you could rent a car and drive 2000 miles, you're much more likely to wait 1 day for a new flight instead of adding 4 days of travel time. And during that day of wait you'd considered yourself stranded, even though you could walk right out of the airport at any time. Emergency options exist, like calling an ambulance, but it doesn't change the fact you're still stranded. You kids would be complaining endlessly about being stranded in an airport for one day, let alone 9 months.
If you're on a cruise ship that loses power on high seas, just because you can get into the the emergency life boats doesn't mean you aren't stranded until something more reasonable and accommodating arrives.
That's the way the word is used in casual conversation.
What's so wrong about calling the crew stranded? Their planned means of travel was "grounded" due to safety issues. Sure, lifeboats existed, but those are for emergencies. This wasn't an emergency. So, they're just regular "stranded" until another vehicle can come and do an unscheduled pickup. Which is what happened here.
This isn't rocket science people. Wait, actually it is :)