Alternate interpretation: Cook made up a cover story because Jobs' health wasn't public knowledge.
It makes for one hell of a story; but, I think the better story is to think of a man who spent his last 24 hours alive with those closest to him--his family.
There's no doubt in my mind that the liver transplant was directly necessitated by his pancreatic cancer.
Given that Cook no doubt knew Steve was about to die, I don't think it's reasonable to think he would tell the truth. Just imagine what he might have said if he had.