In civilian life the boss makes a mistake, it costs money, in the military, the boss (CO) makes a mistake, you pay for it with lives.
STROKE-- The capt doesn't drive. sorry.
MALFUNCTION-- The Capt should have known.
SABOTAGE--Nuke submariners are perhaps the most vetted people in the world. Sorry, this isn't a shoe bomber.
CLANDESTINE--We don't order our subs to "clandestingly strike the bottom".
It don't wash. With one sailor critical, the Capt screwed the pooch on this one.
"CLANDESTINE--We don't order our subs to "clandestingly strike the bottom"."
There's a first time for everything. Perhaps he didn't hit the bottom, perhaps he was attacked? The Navy would keep that info close until it wanted to release it. And you don't get canned for being attacked - its what they do.
Sabotage - it can happen. People aren't computers, you can't tell what they'll do.
Malfunction - the captain can't be held responsible for hidden design flaws that realize themselves quickly and out of nowhere. Doesn't mean they can't courtmarshal him for it, but he'll win. And he'll be given back his boat.
stroke - on second thought, for health reasons he'd be relieved.