A great and very thorough analysis. And by your post this pulley could/should improve low speed cooling.
But what bothers me is that this product was stated as showing “AMAZING” results. Even with your extensive post there is no statistical data supporting this statement. Or what effect it may have at higher RPMs.
It would be honest and fair of the seller to state that his product in theory should reduce coolant temperatures, but is as yet untested. The buyer should be informed that they are in fact the beta testers.
This type of marketing is at best assumptive and at worst misleading and deceptive.