Edukator is “troll” as a warning to others (-: I forget the exact circumstances now.
Junkyard is “lazarus” because he came back from the dead. IIRC we overturned a life ban for some reason, probably profuse apologising and grovelling. I think it was Christmas also.
There’s no underlying ‘special’ reason other than Mark thought it was funny AFAIK. It’s an Admin priv, mere Moderators cannot change it. (I doubt that’s a priv I could trust myself with so it’s probably for the best. It’s the same logic as giving an Aspie geek a Dymo).