Fubar
You are playing ostrich. You need to consider the effect of cold shock, followed by the sea spray & windchill. Based on the met data in the press report conditions were equivalent to North Sea summer conditions where an immersion suit and multiple layers would be required for the passengers.
See page 17 here:
http://www.ukooa.co.uk/downloadabled...K_Coleshaw.pdf
And remember that you need a survival time to be at least 1.5 times the best rescue time.
If this aircraft was bought from Air Logistics (N180AL) does that mean it had sat tracking and ALERTS?