@langleybaston: "I do hope he meant imploded .......... and even that is very difficult to believe."
Given that the cabin pressure is usually maintained at the equivalent of a pressure altitude between 8000 and 10000 feet asl, then it would "normally" be at below sea level pressure when the cabin was almost back at the surface if no "adjustment" had been made from the pressure at cruise.
However, I have also seen comments in other reports that if the cabin enters the water with a rupture allowing water ingress at the end that first enters the water, then the opposite end (which in this case could be the tail), would have air inside that is progressively compressed during the sea entry process by the wall of water entering from the end that the water was coming in, leading to a rapidly increasing air compression in the remainder of the cabin to several bars pressure at the point of rupture. So perhaps that is what the commentator was referring to? If that was the case then only one end of the cabin would have "exploded" and examination of the complete remains of the fuselage would likely confirm or deny that hypothesis?