Conduction through the bottom of the pot, which is in direct contact with the bread, might be an important part of it. However, if the heat transfer is much more effective, why doesn't it burn the bottom side?
However my theory is that the dough itself conducts heat better the denser and wetter it is. The bottom of the dutch oven transfers the heat very quickly, but also right at the beginning, when the dough is densest and wettest. by the middle of the cooking time, when the dough is likely to burn, it is actually the coldest part of the pot.
Baking stones are designed to balance specific heat and conduction so that you don't just end up with a burnt crust on a ball of raw dough.
I couldn't get the recipe to load -- is the loaf put into a hot pan, or is the pan heated with the dough? In the latter case the whole cooking process is slowed down to allow the dough to rise a bit extra before it starts cooking.
However my theory is that the dough itself conducts heat better the denser and wetter it is. The bottom of the dutch oven transfers the heat very quickly, but also right at the beginning, when the dough is densest and wettest. by the middle of the cooking time, when the dough is likely to burn, it is actually the coldest part of the pot.