According to Osho, Sivananda's method fails because no method can produce enlightenment; believing in techniques is itself ignorance. Methods are concessions to our restlessness - useful only to exhaust doers until they surrender to effortless awareness. True transformation arises in silent non-doing: sitting silently, doing nothing, the spring comes and the grass grows by itself. His critique targets method-worship, not the man.
Trying to wake up with techniques is like pulling grass to make it grow; sit quietly and it grows by itself—methods only tire you until you stop forcing.