The problem is that they will always have certain sectors of the community yelping about their "need to know". And I don't mean the media either. You will always have some interest group jumping up and down because the gvt hasn't done x or won't tell them y.
So you tell people nothing and they start to choose not to fly because they are worried about security, and you will have some anti government group yelping because "the Government doesn't care about the security of ordinary Australians", then the conspiracy theorists jump out of the woodwork about "Government cover up because they won't say anything" (and if you think conspiracy theorists are just loonies who would believe anything and aren't worth responding to, have a look at today's articles regarding the use of one of the world's most powerful telescopes just to prove that the Yanks really DID go to the moon).
The sensible mean is that they tell people the most obvious security measures and keep their mouths firmly shut about the ones that they don't want to make public.
Don't you think that the people in the industry who publicly state that there are loopholes to be exploited is more of a worry? Just a thought...