Is it not just survivorship bias? Nobel Prizes are often awarded decades after the fact, and (except in a couple edge cases) are never awarded posthumously. Being long lived makes you more likely to receive the prize in your lifetime, not necessarily the other way around.
They are never awarded posthumously. But my completely unreliable gut instinct is to believe that most honourees are in their 50s and 60s, and that too few people die before that age for it having a significant impact here.
Plus, of course, nominees tend to be very similar in most regards including age to the eventual winners.
On the contrary, consider Ralph Steinem [0], who was awarded the Medicine prize in 2011, three days after his death. The news had not yet reached the prize committee. There are a couple others[1,2] from decades past that were nominated before their death, and the committee selected them after their death, but that loophole was closed in 1974.
