All the "No-Thumb" stuff is nonsense. Some teachers also insist that women should never use the thumb, that use of the thumb should be reserved for men. This is just superstious nonsense. My teacher Gulam Mohammed Khan (cousin of Sultan Khan) uses his thumb and so does every competant player I ever worked with in India. I suspect it comes from some backward idea that use of the thumb slows down the player. This is as stupid as trying to type a 500 page manuscript with two fingers. Call me Anglocentric but the harmonium after all is European in origin and there's no logical reason why the finger techniqes used to master Bach can't be effectively used for Hindustani classical.