Which model of float system was installed on the accident aircraft?
Must it not be activated until entry into the water but would self inflate if "Armed" by means of saltwater immersion switches?
The Cougar 91 Accident Report contains discussion re the various models of float systems and the procedures that pertain but that tragedy occurred some time ago and there might be differences today than noted in that report.
Perhaps someone familiar with the aircraft in question can address the workings of the Float System on this particular model or configuration of the accident aircraft.