I liked Disaster 1990, too, even if it doesn't bear the slightest scrutiny on a storytelling level (where are the helicopters, international relief efforts, science don't work like that, etc) before you get to asking why Bill didn't mention any of this in Invasion or Savage and why there is not even the slightest hint it ever happened. It's episodic, daffy post-apocalyptic adventure in an intriguing setting and aimed at boys who like hard nuts shooting and explosioning things, as one would expect of 1979 Twoothy. Wasn't long before this that Dredd was fighting a car called Elvis on the moon who was going around robbing oil, so I'm not inclined to judge D90 as harshly as others.