This was the response to a specific accident where an instructor was demonstrating the use of rudder to pick up a dropped wing whilst holding the aircraft in a stalled condition. There is nothing inherently wrong with holding the aircraft in the stall however, if the wing drops, standard stall recovery should be initiated and rudder should not be used to pick up the wing.
This was a very non standard technique, and the Trainincom was aimed at making other instructors aware of it, and its inherent dangers. I doubt that such a technique has ever been taught on a UK FI Course and therefore; does not fundamentally change the way the teaching of stalling should be conducted.