The Oklahoma engine was extremely high-time and high-cycle and part of the large number of PT6s that were having blade issues (most replaced by now, I believe).
I can tell you for a fact the engine that was involved in the Michigan crash was running on impact (Pratt can and did nail it down to almost an exact power setting). Pratt, the experts, tore it down to the bare case, with the NTSB, FAA, Cessna, McCauley, and Martinaire all present. Many, many photos were taken every step of the way documenting everything that was found. The NTSB corroborated this with data from the Garmin 696 onboard to produce a plot which was consistent altitude and speed wise for the power setting Pratt estimated.
Seriously, we're to believe they all are in cahoots to cover this up? For a random cargo carrier? Or the industry? Or Pratt? Then why report on the Oklahoma incident, or the many other Pratts losing blades? It's reported more on Caravans because they're singles, and a twin can limp home on one.
It's terrible what happened to your son. No one deserves that, much less at such a young age. But your theory is honestly completely unrealistic. Spatial disorientation and CFIT are very serious problems that affect the industry at every experience level. Any pilot, no matter how skilled, and flying any airplane, can fall victim.