I expect a large reason for the new legislation is to give police/courts powers to inflict significant penalties on idiots who try to use these devices near airports to harass pilots. I understand there have been a lot more incidents of this occurring in Australia recently than appear in the news.
I have found Customs to be very good, but the variation and duplication of legislation between the states is a bit baffling to me. Maybe common sense will prevail in the medium term for amateur astronomers to legally/responsibly acquire and use modest power laser pointers ... without having to pay registration fees ($154 every three years) to "carry" a dangerous weapon which for many of us is permanently attached to a telescope as a finder.
To me, it's a matter of finding "balance" in how these laws are applied, and settling on a nationally uniform approach once a good balance is found.