Why Desmond is so special…
I tried to find a logical (in the sense of Lost) explanation for this question. I believe the reason is this; he exposed the nuclear radiation and/or the electro magnetic radiation in the hatch from a very close range, for a long time, continuously. So he is not special for being “Desmond”, anyone who stays there too much , becomes durable to radiation and move the cork without being “Jacob” or the protector of the island.
So do we know anyone stayed in the hatch for a long time other than Desmond? Radzinsky and Kelvin. Radzinsky committed suicide by putting a shotgun in his mouth and firing it, creating a blood stain on the ceiling as Kelvin said to Desmond. I always doubted it, maybe Kelvin killed him or something made Radzinsky crazy. I believe, Blacksmoke did not want anyone to push the button forever so he tried to killed Rad and Kelvin in some time. But he could not kill them because they were special (not for being candidate but because of the hatch’s radiation). So he made (manipulated) one of them to kill the other one, which would make harder to push the button in every 108 minutes for one person. In the struggle, Kelvin manage to kill Rad (he was a soldier anyway) and survived. However something that Blacksmoke did not expected happened: Desmond came to the island (as Jacob planned).
This is what i can figure out for now… thanks for reading..