With now over 500 views, I conclude this puppy won't hunt. So, here is the quiz answer. Don's "quirk" was the following:
Don Downie CFI insisted each of his primary training flight students log instruction up to and including at least solo in a glider BEFORE he would accept them for primary training leading to the rating of Airplane, Single Engine Land, the FAA's ASEL Private Pilot Certification.
Don, who was also a CFI-G, felt primary instruction in a towed to altitude glider was essential to develop and hone the experience and skills also necessary for powered flight mastery. Soloing a glider gave experience in reading the air, working with the wind direction, seeking lift, attitude management, glide angle experience and altitude preservation.
A primary glider student developed these skills in being towed aloft behind a powered tow aircraft, managing the glider's climb behind and possibly somewhat above the tow aircraft, never raising the towing aircraft's tail by the tow line, separation from the towed aircraft with turn to the left, while the towed aircraft always turns right and keeping perspective as to exactly where and how far away was the landing airport runway, heading and wind component. These skills developed over time aloft transfer well to ab initio powered flight instruction.
Don taught his daughter Dana Downie to fly both gliders and powered aircraft, plus a host of other student pilots. He was wonderful pilot and
instructor.