Nobody has talked about the role of the regulator here. The engineer held a license issued by an aviation authority with skills and knowledge requirements defined by them, arguably significantly dumbed down from what used to be required. The manual he was using and which you could make an argument was not fit for purpose, was approved by the authority.
industry on both sides of the Atlantic have actively pushed to marginalize and neuter regulators. This works great and saves manufacturers and air operators tons of money until the airliner dives itself into the ground or the whole rotor comes off the transport category helicopter at 2000 ft AGL.......