The police seems sure about where to look.... For his phone. So that tells me the phone pings, GPS info if they have it from Google, the state of the phone (sleeping/damaged or not) all point to the Cape Byron area. It might have entered water though, so they cover all bases and send in divers.
IMO the volunteers may be wasting their time, by following info from those who can't be named, and keep searching Broken Head area. MOO JMO.
ps.
@Aron.Wor this is how you post your theory, by using 3 letter words for disclaimer