I would think only Houdini himself could remove intact a helmet with its D rind is placed over the hook with the seat locked - even with the ears removed. It is quite secure.
You can attach the loop once and leave it attached semi-permantly. It easily tucks into a space under the seat when not in use with the seat in the down position. That way you don't need to do any modifications, or worry about it being fiddly to take out the tool kit before you can stow your helmet, etc. I believe that this is the intended use pattern, and that it is so that the wire loop doesn't come of due to vibration that the ears were designed into the hook. My 650 was delivered with the loop already in place.