It's not a question of whether it's "good news", but whether it's a plausible chance of occurring (or rather, whether it's a "big-enough-feeling" probability).
From the quote, it sounds like its a question of whether odds lower than one's prior should increase or decrease excitement when the stakes are high.
From Ezra Klein:
Okay, technically, winning the money would be very weak Bayesian evidence that the initial probability estimate was wrong. Still a very good quote.