Nah, that was an awful retcon. Originally in the pilot it was stated that the exterminations where done to prevent overpopulation in hell, they just decided to add that in the Episode 1 to make heaven look like "the bad guys", even though they are far from it. And if hell where to rise up against heaven, woudnt that make hell the bad guys?? (I mean its bad enough that said hypothetical army is composed primarliy by bad people. But trying to use it to attack heaven?? Wow, thats evil.)