i used to moderate a site a while back... sometimes you just lose people. it happens. something happens that finally makes them think they don't want to deal with the site anymore, then once away... they realize, hey... i don't miss it!
all the best wherever he may roam. i'm no longer involved with any of the old site i used to moderate.. yet speak to, hang out with and eventually married(!) people from the site... or i guess... a person... only married one.