In the Lynx world we are often the only asset available due to where we operate in the world, N/S. Atlantic, Counter-Piracy Ops on the Horn of Africa etc. This means that the choice as you show in your post is:
"Do I attempt a SAR with the equipment, personnel and training I have, or do I standby and do nothing?".
Just because SAR is not the primary role of an aircraft it doesn't mean that it shouldn't be conducted by that aircraft. All RN pilots and observers are trained to winch. The observer is the "trained winchop" and the AET the "trained winchman". Yes it would be lovely to have a 4-man crew, 4-axis autopilot, space for a TV cameraman from Highland Emergency and all that good stuff that SK3/6 has but we don't so we crack on with what we've got.
My point about it being a secondary role is that for the Lynx (primary roles Surface Search and Attack, Sub-Surface Attack and Force Protection), is that it is an official secondary role for us. When we train we call it "secondary roles training". Not that it isn't important. Everyone who flies the Lynx realises that flying events like SAR and loadlifting are always "real" compared to more synthetic training such as CASEXs etc.
As regards the tragic HMS Portland crash, the cause was never defined by the AAIB. I remember something along the lines of "crew reacting to an unknown real or perceived emergency" causing them to conduct the "crash checks" (which involves cutting the engines) during a phase of flight when successful autorotation was impossible. As this happened before I joing the Lynx fleet I don't know what the SOP was at the time but I can assure you that we would not now consider winching someone from the sea at night. I would definitely consider launching as a Search asset though as flying around LL over the sea is our bread and butter.
I don't mean to appear arrogant but for me it boils down to the choice I outlined at the top of post. It is up to the Lynx Flight Commander to ensure that his crew is as ready as they can be for all of the roles that we are required to achieve, including SAR.