First, I have no idea what happened in this case. In response to the posts touting heavy metal as the answer, I have to agree with Russ Reilly. As long as the aircraft is properly equipped, the pilot is prepared and a realistic plan to accomplish the flight is in place, the number of engines is not material. A good autopilot is a significant advantage over a second engine.
I'm less enthusiastic at the idea of night, over water, single engine. Forced landings to the water are problematic in the day time-I'd hate to try it at night.
Offshore is different. The weather is different, less convective-except when it's more so. The "look" is different. It's hard to explain, but not having a positive visual altitude reference seems to make down an imprecise term- you could be inches or tens of feet up. Look down on your next flight, you'll see the surface whizzing by with a rate of closure difference fore and aft, and as it moves by laterally. That's not as definite a data source over water, at least not with the precision your mark-1 eyeballs are used to interpretting.
Lose your "down" and a horizon, you're IFR. Some days, it could be a thousand feet and it looks like inches until you sight something to reference by scale. If you don't have a well defined horizon, you'll find yourself hunting in pitch before you realise conditions aren't what the numbers present.