The quote seems to me to be about how, if you predict something is only about 35% likely, and that thing happens, that's not sufficient evidence to assume you predicted wrong or to throw out your methodology. The line about the million dollars looks like an example to back up the prior sentence, "that's a pretty good chance". Other than that example, the quote doesn't seem to be about excitement at all really.
Okay, that may be the intent of the argument. Not sure I agree with that, either, though. Silver's model is presumably built from several factors. If in the end it gives a prediction that doesn't come true, then there are likely factors that were considered incorrectly or left out. The "70 % odds" is basically saying "I'm 30% confident that the outcome of the model is wrong." If Obama ends up losing, that doesn't mean Silver knows nothing, but it is evidence that the model was flawed in some meaningful way, as he now suspects. That is, we should update on 'Silver's model was off' slightly more than 'Silver's model was accurate', despite the fact that he had less than 100% confidence in it.
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.