Sorghum flour has a great nuttiness, which is quite a different flavor from any other flour. I don't know molasses flour specifically, but I can tell you that the flavors will be very different from each other. Sorghum flour is also gluten-free and won't hold together like regular gluten flours. If the molasses flour has gluten in it, then you definitely cannot replace it with sorghum without adding a combination of starches or gums.