Christian archer,
You are kind of missing the point and if you are instructing in the UK I can understand why.
This flap up as soon as you touch down is to aid weight on the wheels and give either improved braking for a short strip or in the wet season in Africa just to stop sliding about so much or flat spotting the tyres on extremely hot tarmac.
You are right not to teach your students something you have not had to do yourself and they should not need unless they go on to fly into these sorts of conditions.
I can't believe this thread has gone on and on, it does work, lots of pilots improve safety in certain situations by doing it and no a ppl or instructor knocking about most countries will not need to know how to do it.
If I had to fly by the manual in my float plane then most days I could not do the job, much like an ag pilot. It is one of many advanced techniques that bush/float/ag pilots use that the average instructor does not generally need.