Quote Originally Posted by Splash! View Post
Eh? Pardon my asking but what would actually convince you?
That he won't make another living appearance and other characters actually start to consider him dead.

If he really is dead already, he was pretty weak. Below the Phantom Troupe members, and Killua vastly overestimated him. The opponent was a newborn ant, after all, and this was its first fight! He would have lost to an absolute newbie.