I can't really see why the report is fixating on the serviceability of the seat in the aircraft.
Any type of BOI invariably looks at the organization and culture surrounding the accident. In an aircraft accident, the regulation and supporting documentary evidence are key pieces of the puzzle. What the CAA are saying here is that enthusiasm and good intentions are no substitute for regulation and control. What the CAA have unwittingly revealed, and as Tucumseh and JTO mention, is that for these omissions and oversights to have been quite as systematic across vintage FJ operations as they appear to be, nobody at the CAA was paying attention until 2 tragic accidents occurred in a short space of time.