If it's against the culture to debate then I must be quite the oulaw LOL! The only real "expectation" I know is that we add value, and in my mind explaining why a post misses the mark is adding value. Not to mention a whole lot more interesting than everyone agreeing with each other all the time.
Back to the topic at hand, I see nothing done in Australia that would if done in the US violate the 2nd Amendment in the eyes of the ones making that call which is the Supreme Court. Our 2nd Amendment says, "The right to bare arms shall not be infringed." The Australian public still bares arms. That right was not taken away from them. They just have fewer choices now as to what arms are allowed and which part of the public can own them. The public is still armed, though about half as many are gun owners now compared to prior to the buyback program. Apparently just the reduced supply of firearms in the public was enough to cut gun related suicides in half and eliminate mass shootings altogether.