Silver made a prediction. That’s the deliverable. The prediction was wrong.
Would you mind restating the prediction?
He predicted Clinton would win. That’s the only reasonable prediction if her win probability was over 50%
If I say a roll of a 6-sided die has a >50% chance of landing on a number above 2, and after a single roll it lands on 2, was I wrong?
If anything, the problem is in the unfalsifiability of the claim.
If you predict that a particular die will land on a 3-6 and it lands on a 2, then you were wrong. Predictions are occasionally wrong, that’s unavoidable in the real world. Maybe the die wasn’t fair and you should adjust your priors.
On the other hand, if you refuse to make a prediction but simply say a particular die has a >50% chance of landing above 2, then your claim is non-falsifiable. I could roll a hundred 1’s in a row, and you could say that your probability is correct and I was just unlucky. That’s why non-falsifiable claims are ultimately worthless.
Finally, if you claim that a theoretically fair die has a 2/3 probability of landing on 3-6 then you are correct, but that does not necessarily have anything to do with the real world of dice.