I would have thought a recovery would be necessary to assess the state of the engine at the time of the ditching. Irrespective of all the other speculation, if the fan quit prior to the descent, I would imagine the maintenance organisation would find themselves in the legal cross hairs. Regardless of the rest of the legal conjecture etc etc, the accident will have happened because of one or more of three factors: 1) Icing 2) Pilot malfunction of some sort or 3) Engine out. The last being pretty significant.
I cannot imagine why they weren't carrying an ELT in the aircraft ready to activate in situations where it all goes wrong...