No surprise at all to me. I told him publicly just yesterday it was time for him to quit. He turned the discussion of his hobby into work for himself - "work" in the "four letter word" sense. He's obviously been burned out on being a mod for quite some time, and carried on out of a sense of duty.
It can only do him good to have a rest from that sort of bullshit, and to just plain talk shit about rpgs. Hell, maybe the poor bugger will even get to play some. A husband and father doing paid work only has so much time for his hobbies; if he's tossed aside the "moderating rpg.net" hobby, maybe he'll have time for his roleplaying hobby. Me, I've no idea why anyone would ever choose the former over the latter. Discussing roleplaying is to support roleplaying, not replace it.
Scary thing is, who'll replace him as senior admin, eh?