> His core beliefs include that the obvious goal of the human race is immortality
"We should be allowed to live as long as we want to." Emphasis on the want. I don't find that very controversial.
> that it is justifiable to kill a man if it would remove a spec of dust from the eye of every other person on Earth
No, the setup was one person's torture for 50 years (not death), or specks of dust in the eyes of 3^^^3 people. How much is 3^^^3 people?
* 3^3 = 27.
* 3^^3 = (3^(3^3)) = 3^27 = 7625597484987.
* 3^^^3 = (3^^(3^^3)) = 3^^7625597484987 = (3^(3^(3^(... 7625597484987 times ...)))).
"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." [1]That's a monumentally different setup than mere 7 billion humans on Earth. And it's making a point about the cold cruel calculus of moral utilitarianism, a very common and popular ethical position. Your disgust is precisely his rhetorical point...
(Edit: ...about human heuristics and biases getting in the way of the moral calculus of utilitarianism. If you are a utilitarianist, there is some cutoff of X independent people -- for some very large X -- for which it is better to save that many people a slight inconvenience at the expense of 50 years of torture for one individual. This follows straight from the math of finite utilitarianism. Yudkowsky's position of trusting the math over intuition may not be intuitive for most people, but I'd be surprised if a HN reader did not agree at least with the methodology.)