The point seemed fairly clear. Retraining on a Dvorak held no real advantage. The fact is that almost all people learn on QWERTY so the necessary retraining isn't worth it.
Not to mention the millions/billions of keyboards in existence that would need to be scrapped.
Touch typists don't look at the keys anyway, so you don't need to scrap the keyboard. Windows keymap switcher, or the equivalent in your OS of choice allows you to quickly go back to QWERTY on the (very) rare occasions where what you need to do corresponds with the actual symbol on the keys.
Not to mention the millions/billions of keyboards in existence that would need to be scrapped.