The article, as far as I can follow it, seems to be trying to discredit the idea that we can know what a good measure is, objectively. Okay, I guess I can see that. But who cares? Lives/dollar seems like a good measure to me, and I like it. No more reasoning required. It's my money and I decide what to do with it. And I can still think people who disagree with me are wrong.
Moral realism, metaethics, what is all this crap? Is there more to Effective Altruism that I am unaware of? What are they even trying to argue? On either side?