Yeah, that would destroy all life that currently exists, but it would also essentially re-roll the whole universe, and create new conditions for the development of life that didn't exist before. 'Destroy all life' is one thing, but 'prevent any possibility of the development of life' is a much harder job.
There's still a lot we don't know about the universe. Maybe we can trigger false vacuum decay or some such.
Yeah, that would destroy all life that currently exists, but it would also essentially re-roll the whole universe, and create new conditions for the development of life that didn't exist before. 'Destroy all life' is one thing, but 'prevent any possibility of the development of life' is a much harder job.