I place no value good or bad on nothingness. It’s like when people say “what if x person was aborted?” … well then they wouldn’t exist and you wouldn’t be saying this because they never would have existed. It’s a pretty useless hypothetical.
The question is literally posing an instant elimination of humanity in an instant. Not a slow world ending event which involves mass war and rape and bloodshed and murder, but a flip of a switch which ends any and all consciousness of humans. How can that be immoral with regards to humanity? Of course it’s immortal if we take into account other species, but if we’re just talking about human morality then it can’t be immoral.