Having read Walts book. and considering teh discussion on this leads to that.
It is not just the prevention of backfilling. In fact that description flies int eh face of exactly what Walt is trying to say. you are again in a frame of thinking that is about preventing what the bees are doing rather than working with them. At one point Walt addresses this directly. STOP trying to make the bees do what you want. (Not filling the nest) and help them do what they want to do in excess (expand). Is is the manipulation at the time they are expanding that increases that expansion. it increases it so much that the bees never have a prayer of filling it back in. but when they do . let them. let them pack in nectar to their little hearts content. it will all be honey in the end. honey for you to harvest. Help them they can't make the deadline anyway. When they do miss the deadline they will expand again. You removed a lot of that honey making it easier for them. All you need to do is give them room.
Also take careful note of Walts warning about thinning the honey in the late summer. You can carry this to far.
Another key point. make the manipulation before it is needed. That means be one step ahead of the bees at every turn. add space before they know they will want it. remove honey before they make the decision to start eating it. Anticipate their next move and start the work for them.
That is mostly what I see Walt is trying to get across. If "Keeping the bees from..." is anywhere in your thoughts or words. you are already to late. Watch yourself for thoughts like, "I am helping the bees do..." I think you will find your timing and your focus will be more in line with the management method.