I don’t think anyone is justifying the antisemitic remarks made at that protest (or the three men who did the Nazi salute outside the Jewish museum for that matter), but I don’t agree with your statement that we live in Australia so it shouldn’t concern us. When people are being murdered, kidnapped, displaced, it becomes a humanitarian issue that I think people should be concerned about - regardless of your stance. There are antisemitic people who support the #FreePalestine movement, but they don’t represent the whole movement. Whether you decide to engage with this issue is your choice, but I think showing empathy regardless of where you live in the world is hardly difficult.