I haven't followed the exchange at all so may be missing the completely -- just dipping my toe dangerously in the water as I pass by.
The point may and should have been made that "demand" can be a nominal monetary idea (Keynesian creation of zeros) or "real" demand (a
specie claim acquired by supplying real wealth). I doubt that monetary "stimulation" can increase "demand" in any meaningful sense. All it can do is divert "demand" from A to B, ie transfer wealth from people who create "real" wealth to people who don't.
The substitute wealth produced in response to such diverted "demand" is the seen; what was not produced because real demand was eroded is the unseen. The former is invariably what's regarded as the net fruit of "increased demand", as if it is a free lunch.
I have no idea how a model could address the vexed question of whether the former exceeds the latter, either ad valorem, or (what really matters) subjective value. An attempt to establish whether there is a net gain from "increased demand" one would have to quantify what's lost, which seems inherently impossible. I have no idea how one could estimate what would have been produced but for subverted demand, ie what would have been "demanded" instead? Or, more importantly, what's it's value (not price) might have been.