As Australia sees a resurgence in neo-Nazi propaganda, which is increasingly becoming more organized and visible, this ban would at least stop people from profiting off of celebrating Nazi ideology and prevent disillusioned youth from getting drawn into that ideology. These evil symbols have no place in Australia, and its the duty of lawmakers to protect people from growing threats to minorities and democratic values more generally.
This move will likely blow up in lawmakers' faces, as they're bringing international media attention to an incredibly small group of fringe creepers. The handful of neo-Nazis in Australia need public attention to grow, and the Attorney General just put their hateful ideas in the national spotlight. In addition, not all anti-immigration, or even white supremacist individuals are on the right; it is unwise to lump these people into a single ostracized group that risks pushing them to unite under more extreme views.