Moore didn't seem to care much about having the Awesome characters' origins sync up with their templates'. His Supreme is a human who gets his abilities from an accident. Likewise for Suprema, the Supergirl counterpart. In fact, there's a complete absence of any counterpart for Krypton. Professor Night doesn't have murdered parents or any similar tragedy in his background. Darius Dax doesn't have any equivalent to losing his hair. And so on. I think that says something about how he views superheroes.
But beyond that, Silverfall was a holdover from Rob Liefeld's version of the character.