Normal night ops from Williamtown (which happen nearly every night of the week) don't get publically notified anyway, so if the airspace is active, there's a pretty good chance there was a combination of Hornets and/or a refueller and possibly a Wedgetail operating in there. The only reason that the FA18 to Richmond was publicly notified would be that it would be such a rare event that it would be prudent to advise the locals to hopefully avoid noise complaints.