How Does a Hot Water Whipped Pie Crust Work?
How does this method work? In a hot water crust, when the high temperature of the water and fat emulsion is combined with flour the hot liquid causes some of the starch to gelatinize and swell with water which makes less liquid available to form gluten. This lack of gluten results in a tender pie crust that might be better described as &quot;mealy&quot; when compared to a &quot;flaky&quot; pie crust made with a dough using ice water and cold butter.
Here are some articles for further reading:

https://joepastry.com/2015/american-vs-british-hot-water-pie-crust/
https://foodcrumbles.com/hot-water-crust-pastry/
https://www.cooksillustrated.com/how_tos/5790-hot-water-crust