The Doctor has to will himself to not facepalm at those words.

"You don't get it, so let me put it in very simple terms any pudding-brain can understand. I'm dying. Currently and actively. In fact, I already died once and was somehow brought back. So now I'm dying again."

Or regenerating. He still needs to decide. He's not even sure if regeneration will work after such a death and being brought back. Maybe the energy is all an illusion. Which he might be okay with. Since he doesn't really want to change again.