Bostrom brings us "fine phrases and hollow rhetoric," mostly. Sure, we should do something about aging, but what, exactly, are we failing to do as a society here? He seems to think that the problem is that we're treating aging and death as inevitable, but science already has marched past that position; instead, we now know that aging is part of a tradeoff involving cancer and is closely tied to maintenance of DNA as cells reproduce in multicellular organisms.
Further, the notion of agency is hopelessly confused by the design of the fable. Humans are deliberately sending other humans to the dragon while the missile is ready to go, in the story, and Bostrom insists that we are supposed to regret this. However, when we move back through the analogy to the real world, then the way that humans send other humans to the dragon is via war. Will ending aging end war? How?
Anthropomorphizing psychopomps may have been a mistake, since it has led to Bostrom imagining that if we just collect all of the psychopomps into one really big mean dragon, and then kill the dragon, that we'll have defeated death. Easy peasy!