Well, his point only makes any sense when applied to the metaphor since a better answer to the question

"Wait, Professor... If Sisyphus had to roll the boulder up the hill over and over forever, why didn't he just program robots to roll it for him, and then spend all his time wallowing in hedonism?"

is:

"where would Sisyphus get a robot in the middle of Hades?"

Edit: come to think of it, this also works with the metaphor for human struggle.