If the OP's challenging a moral intuition that doesn't at some point reduce to commensurability, then I don't know what it is. It asks us to imagine the worst thing that could happen to a random person, and then the least perceptibly bad thing that could happen, and seems to be making the argument that an unimaginably huge number of the latter would trump a single instance of the former. What's that a reductio for, if not the assumption that torture (or anything comparably bad) carries a special kind of disutility?
On the other hand I'm not sure what the post was written in response to, if anything, so there might be some contextual information there that I'm missing.
I'm... puzzled by this exchange.
But, yes, agreed that a lot of objections to this post implicitly assert that torture is incommensurable with dust-specks, and EY is challenging that intuition.
"What's the worst that can happen?" goes the optimistic saying. It's probably a bad question to ask anyone with a creative imagination. Let's consider the problem on an individual level: it's not really the worst that can happen, but would nonetheless be fairly bad, if you were horribly tortured for a number of years. This is one of the worse things that can realistically happen to one person in today's world.
What's the least bad, bad thing that can happen? Well, suppose a dust speck floated into your eye and irritated it just a little, for a fraction of a second, barely enough to make you notice before you blink and wipe away the dust speck.
For our next ingredient, we need a large number. Let's use 3^^^3, written in Knuth's up-arrow notation:
3^^^3 is an exponential tower of 3s which is 7,625,597,484,987 layers tall. You start with 1; raise 3 to the power of 1 to get 3; raise 3 to the power of 3 to get 27; raise 3 to the power of 27 to get 7625597484987; raise 3 to the power of 7625597484987 to get a number much larger than the number of atoms in the universe, but which could still be written down in base 10, on 100 square kilometers of paper; then raise 3 to that power; and continue until you've exponentiated 7625597484987 times. That's 3^^^3. It's the smallest simple inconceivably huge number I know.
Now here's the moral dilemma. If neither event is going to happen to you personally, but you still had to choose one or the other:
Would you prefer that one person be horribly tortured for fifty years without hope or rest, or that 3^^^3 people get dust specks in their eyes?
I think the answer is obvious. How about you?