I think Ammi's premise is that the date you are given as going to die is immutable, unchangeable though, regardless of science or any other factors.
And yes - I would love to know the exact date of my death so that I can better prepare for it, and also draw up a list of 'parting shots' with which to extract bloody, brutal revenge on those who have wronged me without fear of judicial recrimination.
Bliss.