I do not know his spawn timer, but he does still pop.
I was in the hole two days ago, and was puttering around, (not ever really have hunted here), we went past the Jail area down to where the constructs are, and I noticed this guy on track with my druid, we mulled it over, while someone looked up the drops, and we decided to go back and get him. When we got there, someone else had just finished him off dangit!!!
So he does still pop, but it seems he is a random spawn, and those elementals are PH for him.
Just stinks he is level 53, and you gotta kill greenies for who knows how long to get him to pop.
And can someone give me directions to it in the hole i got maps and have explored a bit in there but still not seen him. Does he have a week long pop time or something?