Not sure where you get your info, but this operator follows the RFM recommendation, "armed over water".
This was your quote Geoff:
During the lifetime of this design of float system (which I believe is the same as that used on the Merlin and the Lynx) there have been no reported instances of inadvertent inflation in flight and the many many thousands of hours of their use whilst 'armed' testify I believe to a well designed and reliable system.