SLF
"At what point does a demonstrated lack of professionalism in a complex operating environment override any other relevant components of the accident."
Generally, after the fact, and often not even then.
People who work in association with eachother (vendor, regulator) develop a camaraderie that often trumps duty, and integrity. It doesn't take much in a "complex operating environment".
Why did EASA relax inspections on the TRENT 700 prior to QF32? How did Thales remain on the 330? "Judgment calls" occasionally lay on the lax side of decisionmaking. Unfortunately, in many accidents, the fact that "regulation" is seen as "interpretive" results in the need to polish turds...after the fact
You ask the important question, Sedona.