i think its fairly obvious the reason why its reduced....for the safety of you, other motorists, and those who are working on the freeway.
As said earlier, just cop it. You wouldnt have a good enough reason to avoid the suspension anyway.
I have worked on freeways and its amazing to see the number of idiots going through a 40kph or 60kph section at well over a hundred. When we were working on Calder once, we requested to have the police there, and a guy got caught doing 110kph in a 40kph section. So be thankful it was only 80kph.