It's just like Oku's style. One element of his writing is that even throughout all of the insane things happening to the world, the NPCs only respond minimally to major crises. Granted, he's writing an action manga, not an epic novel, so it is forgivable, but it leads to dissonant situations like this.
It's also probably a little bit that Oku maybe thinks very little of humans in general since outside of the main characters, most people in this story are portrayed as different flavors of stupid and evil.