A different theory. Fire, possibly electrical; attempted diversion to a different airfield to west; comm systems rapidly fail due to fire or are shut down during suppression efforts; pilots soon succumb to smoke; passengers too; plane continues on westerly course until fuel expended.
https://plus.google.com/app/basic/stream/z13cv1gohsmbv5jmy221vrfyiz3vdhbop04
My immediate impression is that this person (ex-pilot) is trying to find a scenario in which the pilots were innocent. It doesn't explain no cellphone calls or some reported course information. The hypothesized fire is required to extinguish itself?