But one cannot compare the general need for SA between a VFR/IFR-OCAS piston operation, and an airliner. The latter flies in CAS (or is under a radar advisory service for those that do bits in Class G) whereas the former has to look after himself, and his biggest challenge is not busting CAS.
I agree with your specific example, but the pillars (as many have described here) of good SA don't change for either case.
I don't suppose I disagree with you all that much but I do think that making very general statements is not educating GA pilots very much.
As already mentioned, SA is a general concept. Bar the basics like MSA, etc, I don't think it is right to say that good SA means doing specific things at a specific time in a specific way. I know Pilots who try and run the show like a script and sometimes loose the big picture as a direct result.
A nice adage to hang your hat on is "plane, path, people" (people - traffic, atc, pax, anybody). Ask yourself that any time something unusual happens and you can't go far wrong.