

Because his original motivation was to impress a girl he liked. Death is a hot chick that he was in to but she wasn’t interested in him. So he figured killing half of all life would impress her.
They decided to make his motivation more sympathetic for the movie. They didn’t think through how his new goal could be better served with the godlike powers he gets.








FYI celery powder has lots of nitrate naturally and bacteria turns them into nitrite. So it’s just a way of getting around FDA labeling regulations.
The net effect is the same.