I'd wondered that initially, but after reading the book, it seems wildly unlikely that he ever could have kept his hand. It was crushed by an 800-lb boulder and lost circulation pretty much immediately. It sounded like an unsalvageable injury to begin with, especially with the built-in time delay of having to summon rescuers, have them get there, and then extricate him, even if they'd been summoned immediately.

It turned out to be really hard for the retrieval people to extract it even after he cut it off. If he'd had rescuers show up right away, they even might have even had to amputate on-scene, though that's a little hard to say because once he was out of there, extracting him in one piece was a moot point.