Arguing whether "all" or just "most" of humans dying is certainly a choice.

Survival of the species isn't enough.

In prioritizing risks I do feel it's a genuine qualitative difference though.

Number of humans going to 1 million would be huge catastrophe, but after a few thousand years it gets back up to billions of people, renewed every generation.

Number of humans going to 0 means that's it. One scenario has many orders of magnitude more missing humans, when you count future lives.