go around from an asymmetric approach with a propeller feathered in training? come on, no one here can seriously suggest that that method is safe,
Depends what you are training on. When I was involved in airline check and training in the UK, an asymmetric approach and single-engine landing was a certification requirement. That was on turboprops of course, with plenty of excess power - if you do it on a piston twin, you don't EVER feather the prop... you simulate zero thrust. Even safer.
An instructor should assume full control of the aircraft when it is necessary to re-brief or debrief the student in flight. This allows the student to better concentrate on what is being said.
Leaving aside that I don't use an Aussie publication to refer to when instructing, it is pretty obvious that rebriefing is not the same as coaching, which you manual does not refer to. What do you do, sit there silently while the guy screws up? Have you ever even instructed? Doesn't sound like it.
the demonstration of the instructor's high standard of airmanship is critical in developing the same in the student.
You don't have to handle the controls to "demonstrate a high standard of airmanship". The student learns by doing, not by watching the instructor doing. This is instructing 101.
You may care to note that, in the airlines, the instructor or check pilot virtually NEVER handles the controls, whether in the sim or the aircraft. He or she does not usually occupy a crew seat, either. You will learn the reason why if you ever progress to airline-level flying. It is the same reason why an instructor in GA should handle the controls as little as possible. Sadly, many instructors just can't help themselves, and feel that they must demonstrate their superior skills (or rhather, their planet-sized egos) far more than is necessary.
i note, remoak, that you only mention knowledge and skill as important for a charter pilot.
Not what I said at all. Read it again...
very few pilots make good instructors.
Errr... yeah. Right. Whatever...