We prefer only active members to be in the members list, though clearly this isn't that strictly adhered to as there's loads showing up who haven't been here for years. It's finding the time to go through them all and retire them.
You tend to find if people make a big public flouncy fuss then they will get 'retired' as part of that. He left and thus his profile is 'retired'. It still exists but is not visible in the members list. It's not banned and could be logged in any time, indeed I think he has done so once or twice since he fled.