Gullible, I can only tell you how HEMS works. The Medical agency is responsible for tasking the aircraft. Sometimes all the details are known and sometimes not. SAR, being a more senior service having been around longer than HEMS I am sure operates on a similar basis.
It's easy in hindsight to be critical of the urgency of any task. However, most emergency services are pre-disposed to launch rather than conduct unofficial triage to avoid the risks of ending up with a fatality after they have declined to respond.
As an EMS pilot I am not medically qualified to make those calls and so rely on the expertise and more crucially, the established protocols of the medical teams to make the launch decision. Sometimes it is overkill (excuse the pun). Most times it is not.
I am not interested in the medical details of this incident until in the air and I suspect prior to launch, neither were this crew. They would simply be responding to the tasking agencies call and get on with it. Fast reaction is the principle and too many opinions in the process would just slow the whole thing down.
I doubt the skipper of the boat would make a commercial decision over the welfare of his crew. Fishing boat crews are a tight knit group. They would have made the call to protect the persons interests. Also I would pay lip services to reports in the press.
Finally, don't forget SAR crews train regularly and I feel sure the conditions on the night would have not stopped them training. The risks are always there. However, if this was a training flight I doubt we would be saying training should be banned because of the risks.
I am sure they will be lessons learned from this but I doubt it would alter launch criteria or the need for top cover as I for one, do not believe they are relevant. Or to put it another way, doing so rather accepts the likelihood of such events and by preventing the flight you avoid the event.
There will be a root cause to this accident just like all the others before this one. Finding it and evaluating that root cause to reduce or even eradicate that risk is far better than mitigating the risks by preventing such flights from occurring.
Apologies Albatross, I missed your post. I think you describe the principles and reasons behind an EMS launch better than I did.