Tuc,
I agree with you again there.
wrt your last 2 statements in bold, and particularly
Airworthiness is not only concerned with engineering aspects, but also with the way an aircraft is flown and how its systems are operated
this still shouldn't be construed as meaning that currency and competence form part of the airworthiness of an aircraft. As you know, issues about the way the aircraft is flown form one part of the RTS, defining the flight envelope for the varying configurations of an aircraft, and limitations on how the systems are to be operated form another. The fitness and suitability of the operator doesn't form part of the RTS.
sw