Also a non-horse person but I have just learned that horses were originally cold blood (from a cooler climate like Northern Europe, normally bigger, think Clydesdale) or hot blood (from a warmer climate like the Middle East or North Africa, normally smaller) and warm blood is what you get when you combine them! Although it's used now to refer to horses that have been carefully bred over many generations to be extra fancy and good at equestrian sports. So this person wants the Porsche of the horse world, it sounds like. For free!