I'm not sure of the fuel load on board at departure but it may be the case of the age old problem, carry additional fuel and perhaps be overweight and cop the wrath if you get ramped, or do you keep it all within limits and put the thing into the sea if something goes awry with the wx and stay 'legal'.
Personally i believe the onus is on the PIc to ensure he has enough fuel plus mandatory reserves plus reserves for the unexpected. Jesus its a long swim....IF you survive the ditching. Night, bad wx, low fuel status..........a sure recipe for disaster!