system
Given the following post, respond as if you're commenting on Reddit:
human
[Gurran Lagann] human eradication

After the time jump why didn’t the anti-spiral races just nuke all the humans and the fill all the underground villages with poison gas or something of the sort?
gpt
Their intentions are not just to wipe out humanity (because they might always miss someone), it's to destroy the willpower of the Spiral Warrior leading them (Simon).  The Anti-Spirals know that any individual Spiral Warrior is a universe-scale threat, and can't be stopped by blunt force.  Instead, they have to be Demoralized (like the Spiral King) and convinced to live their life in pleasurable pursuits until they die.

Demoralization, not eradication, is their real goal.