If Dementors were just dangerous evil creatures roaming out there and occasionally killing unlucky people who didn’t Apparate away in time—like trolls, or dragons—Harry wouldn’t care much about them and their association with Death.
“Humanism” suggests he’d technically want to eliminate them anyway, and as it turns out this desire seems wise. Dementors can breed (asexually) if whatever makes decisions for them decides to prepare for more victims. It happened in canon. In the absence of any Patronus 2.0 this seems like an existential risk or a risk of an unpleasant future for humanity, depending on how the Dementor decision maker works. And again, given the existence of Dolores Umbridge with her canon use of Dementors, I see no reason to believe that every present and future Ministry official will refrain from offering them Muggles. Nor does it seem wise to wait until Dementors start multiplying before reducing their numbers.
Now, Harry doesn’t know all this, but “hole in the world” sure sounds like a possible threat to humanity’s existence. He must believe in a non-zero risk from Azkaban. Logically Harry should ask if this risk exceeds the Star Goat or Anti-Pascal’s probability. (Example: the chance of cryonics working, in any particular case, seems to far exceed the Star Goat probability of it interfering with or preventing an afterlife.) And neither his pessimistic mentor nor his conditionally pro-death mentor seems to consider the chance of ending humanity through killing Dementors worth mentioning.
“Humanism” suggests he’d technically want to eliminate them anyway, and as it turns out this desire seems wise. Dementors can breed (asexually) if whatever makes decisions for them decides to prepare for more victims. It happened in canon. In the absence of any Patronus 2.0 this seems like an existential risk or a risk of an unpleasant future for humanity, depending on how the Dementor decision maker works. And again, given the existence of Dolores Umbridge with her canon use of Dementors, I see no reason to believe that every present and future Ministry official will refrain from offering them Muggles. Nor does it seem wise to wait until Dementors start multiplying before reducing their numbers.
Now, Harry doesn’t know all this, but “hole in the world” sure sounds like a possible threat to humanity’s existence. He must believe in a non-zero risk from Azkaban. Logically Harry should ask if this risk exceeds the Star Goat or Anti-Pascal’s probability. (Example: the chance of cryonics working, in any particular case, seems to far exceed the Star Goat probability of it interfering with or preventing an afterlife.) And neither his pessimistic mentor nor his conditionally pro-death mentor seems to consider the chance of ending humanity through killing Dementors worth mentioning.