As I understand it, the math is in the dust speck's favor because EY used an arbitrarily large number such that it couldn't possibly be otherwise.

I think a better comparison would be between 1 second of torture (which I'd estimate is worth multiple dust specks, assuming it's not hard to get them out of your eye) and 50 years of torture, in which case yes, it would flip around 1.5 billion. That is of course assuming that you don't have a term in your utility function where sharing of burdens is valuable- I assume EY would be fine with that but would insist that you implement it in the intermediate calculations as well.