Lyman, With experience and if I was flying, I could pull 5 g without a g suit for a minute, or 6+ g for a minute with the 'speed jeans' on.
Jimmy Leeward was experienced and he was flying. Older isn't always disadvantageous. If he had slight hypertension, he could withstand higher g than a 'young puppy'. What matters was how well he used his muscles to keep blood where he needed it.
You still haven't explained how the trim tab failure could occur as a result of pilot incapacitation, whereas, if the trim tab loses integrity it is no longer providing nose down trim and we already have an example event that shows 10+ g can result. That is sufficient for prompt GLOC.