On a related note,

If you think your own life is valuable enough that you're not willing to take on an eighty percent probability of dying in order to protect all the prisoners in Azkaban, his Slytherin side observed, there's no way you can justify taking a twenty percent risk to your life to save Bellatrix and Professor Quirrell. The math doesn't add up, you can't be assigning consistent utilities over outcomes here.

The logical side of him noted that Slytherin had just won the argument.

It seems the author is flat-out telling us that Harry is deliberately acting irrational, and commends him for it. Curious.