HC - I understand your point and largely agree with you in relation to a predisposition for 'self-contained' let downs, flying around in marginal VMC, etc. on SAR but I'm not sure it's particularly relevant to this incident.
The average let down on SAR is usually as safe or even safer (especially at night) than the average ARA to an oil rig in my opinion, having done both.
With the advantages of NVG, FLIR, AIS and another couple of pairs of eyes and ears on the aircraft tuned in to what's going on, SA and indeed the visual sight picture are often significantly improved.
Of course, there are the awful, dark, foggy, stormy, [insert further terrifying adjectives here] approaches, scraping in to the significantly reduced mimima that SAR is granted which obviously - necessarily - expose the aircraft and crew to increased risk but these are the expection rather than the rule.
I think any implication that the crew here were pushing the limits or operating at an increased level of risk seems misplaced - an overwater letdown on what (as far as I can see) wasn't a particularly awful night weather wise is bread and butter for a qualified crew and a necessary part of the job.