Sadly, according to the reports I've read three people died as he did not sound the general alarm.
While his Mayday call was not up to the usual standard, I suspect this was very much a "red mist" moment. You do not expect a ship to break its back in a slight swell in that appears to be an anchorage.
I was told of the ultimate cry for help by the person who made it. A work colleague was at home. Heard two shots from next door, a pause then a single shot. Dialed 999 and was in so much shock could only squeak the word help. The call handler must have had a sixth sense that something catastrophic had happened and three police cars were dispatched. A chilling story.