"Qualified Glider Pilot"
Unfortunately, we don't know much, if anything, about his glider qualifications. We don't know if he took a weekend glider transition course or had 1000 hours.
As a glider pilot myself (and A330 Capt), I was surprised when I first learned that Bonin was a glider pilot yet failed to push the nose down in reaction to a stall warning that persisted for over 50 seconds! Obviously, in the glider, there is no other recovery available. We fly on the edge of a stall routinely, recognizing the impending stall condition by feel - as there is no audible warning system.
I remain a strong advocate of hand flying aircraft such as gliders to counteract a case of flight director addiction ( which I will go out on a limb and accuse Bonin and Robert of having).
In 1986 we could assume that anybody that showed up in an airline course already had thousands of hours of round-dial instrument flying. Checking out in an advanced aircraft (757 at the time) was a matter of teaching the automation. Now, the assumption of those skills is a poor bet. Throwing a guy out of flight school into the right seat of an A320, then A330/340 and rarely if ever practicing those FD off skills is like asking an adult to perform the piano song he learned as a child - on stage, under pressure, with no notice.
Yeah, I DO think my glider time has helped me keep some skills. But only because I put some effort into it. I try to think about the aerodynamics, the micro-meteorology, and such things because they are key to success in a glider.
It's easy to sit back, do whatever the FD says (it's never been wrong yet...), punch on the AP, and type my way to the destination. That does take knowledge and skill, but its a different knowledge and skill than hand flying the machine with out any automation, in alternate law, at altitude, in a storm at night. The later requires some practice. Practice few long haul guys get much of.