It says initial temperature, and I think you'd want to be at coals not roaring flames at that point so they probably don't add any more fuel during the bake. It probably finishes at more like a "normal" modern bread baking temperature which is still 450ºf or higher.

And we're talking about a six pound loaf apparently which is just massive. I'm a pretty experienced bread baker, have done it professionally albeit briefly. My baker's intuition is that this would work.