I think the absence of NVD is a bit of a red herring considering the helicopter was fitted with FLIR equipment. If lifting a casualty from a vessel, it would be normal to illuminate the lifting area with deck lighting. For sea and cliff rescue, there is a searchlight. NVD is more likely to be a hinderance than a help in most rescue operations since the pilot(s) should be positioning according to the directions from the winchman.
Gouli - I am assuming from your comments that you haven't done SAR with NVG. Whilst the actual rescue is usually done on white light (or mixed with NVG) it is the getting to the rescue where NVG really come into their own.
DB - the best 'real world' view is out of the front window and with NVG on they would have seen the rock long before it became an issue.
Rotorspeed - as previously mentioned, FLIR does not look through cloud since it relies on the thermal differences between the objects it is looking at - in cloud the water droplets attenuate almost all the thermal energy and make everything look uniform.
P3 Bellows - it was mentioned earlier ISTR that the IAA wouldn't allow civilian use of NVD - a bit behind the times really since just about everyone else does it now.