Crazyasscrackpotending: It's revealed that the nonmen/inchoroi are suffering from massive pervasive delusion. The Ark never fell from the sky, the inchoroi are nothing more than a branch of the nonmen changed over millenia. They conceive of a grand scheme to evade damnation, but know that it will only work if they believe their own lies (smelling plato) so they invent the inverse fire to compel belief. It's the last thing they do after constructing the ark, filling it with bodies, and setting off an explosion across gogongorea destroying viri. LOL
EDIT: Just adding this bit, Bakker seems bent on genre-bending and reader-expectation-twisting, the above would fit since the story WOULDN'T actually be scifi at all (no aliens, all fantasy) and he could get rid of all the other things like stars being other suns. Earwe really is the center of the universe, it's not like our world, there is nothing but stars circling above.