He's not dead. This is the last we heard from him, as reported by undoall (also AWOL):
21:50 <@undoall> I am okay. I apologize to you, Seisatsu, and any other sushi who may have tried to reach me. Dunno, words fail me at the moment (actually hour, I've rewritten 3 times). Apologies are cheap consolation, though.
To be honest, I think he was just depressed and did not want to carry on running a community of people whom, towards the end, he barely engaged or talked with.
It's quite sad but I hope he'll be happier going his own way.