Ideological proponents of the scheme point to a decrease in *gun* homicides or *gun* suicides.
That is statistical trickery. What counts is the overall homicide and suicide rates.
The gun law had no effect on them.
The other thing to consider is if ISIS or any other such extremists acting either alone or in a group were to want to target Australia, they would likely have little or no use for the strict laws there (as recently seen in France and other parts of Europe). Australia, due to it’s location, is not an immediately accessible target for logistical and publicity requirements for such persons like Europe and North America both are and that is quite possibly why such an attack has not happened there, yet.
And if guns were not employed at all, large trucks or bombs or other such things could easily be used to carry out a horrible act as also recently witnessed in France and England (someone in Brazil this week killed four children and a teacher by setting fire to a nursery school).