The minister doesn't find out about "delays". The minister only finds out about airspace closure. Hence, no closures- only 'delays'.
That way the managers can stand in front of a senate estimates committee and say "we do not have a staff shortage- we have adequate staffing".
Perhaps you could print out the relevant transcripts to read to help pass the time next time you are holding...due to staff shortage (cough cough)...I mean 'operational requirement'?