The guy, knowing full well Jinwoo plans to add the nigh-invincible dragon as his pet: "Sure, why not, he could probably delete the country until he finds it, now that he knows the corpse exists."
Also, what I hope Jinwoow would say next chapter: "Alright, new plan. I take the rune too, and I leave the immortal dragon here to defend the US in my place. ALso, if I need him I'll take him back, obviously."
I mean surely the dragon that was defeated by 5 nation-rank hunters can fill the spot now that he's gotten shadow immortality.