Could you clarify what you mean when you say that Eliezer is "being coy about" prioritarianism?

As for me, I'd never heard of prioritarianism before; having just read the wikipedia article (which does have some style disclaimers and "citation needed"s, so perhaps is not the ideal source), I don't think it addresses either of my objections. It does at least attempt to capture some of my intuitions about the Specks vs. Torture case.