Gliding and Air Training Cadets is IMHO they very best way to go.
I got ten hours knocked of my PPL back in the 80's because of my gliding experience. Seems it might be more these days.
But much much more than that is the quality training he'll get from some of the old senior's in the gliding movement who will teach him just for the love of the sport rather than a monetery or hour building reward. He will learn things about meteorolgy, aerodynamics, paddock landings, and composite stuctures to higher degree than your average GA pilot. With all due respect to the many above average GA pilots of course.
He will also develop a great feel for the way an aircraft fly's, and a true appreciation for the beauty of flight.
Regards
M