It seems like the metaphor is a bit meta? Tautological? Death is represented by death. This is a minor point, but distracting. Still... I hope for a well-supported contingent of warriors to slay the dragon. If not now, eventually.
I think the point this is trying to make is that we accept death of old age as a natural fact and think it is odd to want to "solve" it, but wouldn't accept it at all if it were caused by some personified actor?
Of course we don't "just accept" it, we have long considered a large fraction of deaths "too early" and worked on postponing them with various treatments.
Just because you don't die of old age doesn't mean you wouldn't die. As long as time exists, you will end.
That's why dragon is aging, not death.
It's a pretty common metaphor in transhumanist circles. I remember this piece comparing the elimination of "natural" unhappiness to the advent of painkillers making a strong impression on me: https://www.hedweb.com/hedab.htm