Dunstan's case didn't reach the courts. That's not a bad thing (certainly not for him) but the arguments made are far from the legal arguments that I believe would have been applied in court. And I think part of the reason why New South Wales police did not charge him with anything is because they knew the arguments that would have been made in court.
In court, I would expect a lawyer arguing this case to base things on the precedents of Zecivek v DPP, and R v Conlon, and they'd have won on that basis. These are still the two most important court cases in Australia concerning both self defence in general, and specifically self defence with a firearm. Both of those cases were more serious than Dunstan's - Zecivek and Conlon actually killed the people they were defending themselves against, and Conlon was drug affected (impaired judgement) and protecting his illegal drug plantation! Self defence still applied in both those cases. The Conlon case in particular is significant because it still applied even though Conlon was committing other serious crimes at the time, which means self defence continues to apply even if other laws are not being fully observed - and that has direct relevance because even a technical violation of firearms law (which could have been argued in Dunstan's case) does not extinguish the right to self defence, even if a firearm is used.
Yes, your are correct. I read about those cases.
Self defense is still legal.
Help me out here. Was the firearm used in either of those cases legally licensed?
Were either of the defendants charged with firearms charges separate from the manslaughter/murder charges?