He said 'none of the others' or something like that. I think not to accept it is the correct choice by the way. It smells of the handshake in OiaLT. Who are 'the others' is open to questions. It might be everyone to whom the Founder offerd the amulet and so, probably, no one has accepted it, provided getting it from the Founder is the only way to obtain it. Yet there might be other ways, or the Founder with 'the others' did't mean everyone who was offered it but some smaller group of some kind.
I personally think he offered it to a certain small group of players and no one has accepted.
By the way, why do we assume that Thanatos at some point has died in Eternum? I mean, probably he died quite some times when he was a noob, but he might well have never died since he become 'someone' in the game.
So far we only have seen him being injured by Orion and that was by no mean a killer blow. (Well, actually loosing a hand can kill you by the lose of blood, but whatever... Sure not instantly).
So maybe Thanatos can be killed, it just takes a huge lot of effort.