I don't disagree with that analysis, but remember, the island gave him back his legs. Think about the scene in the tour operators office...Locke yelling that he could do the tour, that he shouldn't be told that he couldn't. While the kidney donation debacle probably resulted, ultimately, in this parallysis, I think the loss of the use of his legs was the most devasting thing to him. The level to which he felt indepted to the island for giving him back his legs is unimaginable. And when he "saw into the eyes of the island" is when the island told him what was expected of him.