I think that this makes a lot of sense if you are doing a lot of your cooking this way. I never cook this way so it wouldn't make sense for me. I am really turning my extra wood into an outstanding soil amendment, and storing carbon. So, I think it depends on your motivation for making biochar.
I think it has possibilities, but at a certain point in the burn you will have to choose between "more heat for cooking" (stir in more oxygen) and "making good char" (pack down the coals and exclude oxygen). My 2c.
The Greenhouse of the Future ebook by Francis Gendron