I LOVE Glenn Gould! - A true artist, he stand up for his beliefs, regardless if ANYONE EVER AGREES or not with him and mind you, I certainly respect his interpretations and cannot wait to listen to one of them - and no, I do not always agree, but we discuss his interpretations in length.
The amazing thing is, I teach a similarly relaxed hand. I do not suggest to sit so low as Glenn Gould demonstrates, I also do not suggest a "dry Baroque sound" at all times - besides Baroque sound should not always be "dry" - often very rich and singing with a Clavichord brightly singing sound. On rare occasions - in order to show / demonstrate a relaxed physical motion - I let my students drape their hand over mine and they get a "feeling" of how the motion "feels" that I am trying to convey - and it usually works very nicely. We always work scales / chords - cadences and arpeggios, shaping a relaxed and beautiful meaningful sound. And we (my students) can play beautifully and accurately very early on, growing into advanced repertoire quickly. I have two students perform in the Bach Complete Works Competition next week and wish them well, preparing conscientiously in the next 8 days. It is not easy to keep youngsters focused, but that is all part of developing maturity and follow through.