He was probably hacked by someone he knows or forgot to log out on a public computer.
It's not impossible to bring players back from retirement, we did it before but it's a policy issue. Since that is a pretty big thing (un-retiring), it should be done only where there's definite proof a bug in the game or us, devs, are responsible for the retirement. If a user somehow got hacked and lost a player, it is not our fault he did. Also, it's impossible to prove the user didn't fire the player himself and then regretted his actions later on. Not saying this was the case here, of course, but you surely understand that it's policy.