Silver made a prediction. That’s the deliverable.
I see what you’re not getting! You are confusing giving the odds with making a prediction and those are very different.
Let’s go back to the coin flips, maybe it’ll make things more clear.
I or Silver might point out there’s a 75% chance anything besides two heads in a row happening (which is accurate.) If, as will happen 1/4 times, two heads in a row does happen, does that somehow mean the odds I gave were wrong?
Same with Silver and the 2016 election.
Admittedly, 538 was pretty good about showing their work after. While individual events suffer from the unfalsifiability issue, 538 when Silver was around, did pretty good “how did we do for individual races/states” and compared their given odds to the actual results.