ED's logic is simple. Makeing a A10C level needs three elements : Model, AFM, Avionics,any of them are time and money consuming.ED can not live without any income throughout the whole development process. So they just earn a little money from model ,then AFM step by step. After the Avionics is complete, the only thing need to do is to combine the model ,AFM ,Avionics and then a A10C level product is done.