I'm surprised that the blades are heat treated before they're ground in any way, it seems a little counter intuitive but maybe it's easier to get the cosmetics that way?
Perhaps you can get a better edge once it has been heat-treated? Just guessing here. EDIT: Finally watching the video now and reading between the lines it seems like the dimensions can change during heat-treating so they are more consistent if ground after.EDIT 2: I listened a little more closely: "After heat-treating... all of our knife blades and many of our components will go through a process called double-disc grinding, where they go in as a blank and heat-treated part and they come out precision-ground for thickness, parallelism and for cosmetic surface finish."