Thanks Barkly 1922.
My recollection in relation to CHOGM was that CAF told the PM that RAAF would have difficulty in maintaining CAP H24 - hence the need for a primary exclusion zone [45NM as I recall] - and a larger alert zone [around 200NM as I recall].
I have no doubt that your recollection of what actually ensued is correct.
Interestingly, the security advisors were having kittens at the fact that the two primary conference hotels were so close to the short final approach paths for either end of the runway at MC. There was simply no way to guarantee that an RPT operator or VIP flight wouldn't 'speer in' to one of the hotels - never mind the odd 'stray' C172.
Anyway, the key point was that there was considerable debate about authorising any Defence arm to 'act in anger' within Australian landmass airspace. Several laws had to be amended. What a pity we live in times such as these that require such measures.