Quick to point the finger arnt you? To me it sounds like something else. Nowhere did I see a mention of being unconfident either. He obviously had enough time to think about his reactions. The plane was turning, he made a correction and got no response. Even with full rudder input.

Did you range check? Was the Rx recently in a crash previous to this plane. A bad crystal sometimes won't show itself until the enigne vibrations hit it. Did you not ANY glitching? Lets do this systematically and see if we can find out what brought the plane down.
Did you check the servo horns? even the best pilots have forgotten to screw down a horn. Put your battery on a load with a voltmeter. Sometimes a battery may seem fine, but when under load craps out.

goodluck

Sean