So f**king what?
That doesn’t make it any better.
The fact is the place was invaded by white fellas .
They killed thousands, they enslaved men.
They raped women, stole children
Stole everything.
Now their descendants don’t want to join in the glee club that sings a song that offends the memory of their ancestors.
Not only did "this" (the sorts of misery you describe inflicted on indigenous people by British invaders) happen a lot, it is often conveniently forgotten, and people do have a right to be upset about it.
Though it also shouldn't be forgotten that the same things, rape, torture, murder, slavery, were inflicted on most of the non indigenous population also. It was a brutal time and the elite British hierarchy enforced misery through much of the world, including on their captive colonists in what would become Australia.
And many people have since come to Australia precisely to escape these sorts of things in their countries of origin.
The real issues are deeper than the misery from imperial British hierarchies of two and a bit centuries ago (who were horrible, but not especially worse than any other ruling forces in the world at the time).
The issues are that the legacy of that invasion has left us a scarred nation, with ongoing, real problems today, some of which are cruelly targeting indigenous people disproportionately to the rest of us. Mind you, it would still be cruel to have terrible child mortality, for example, in an otherwise modern, healthy country, even if it was not a problem really affecting a segment of our population more than another.
The real strength of our nation is that despite the crap dished out to our indigenous people, our first penal colonists, the underpriveleged and those fleeing persecution from elsewhere, we have a strong, healthy, vibrant population that has created a very pleasant place to live for most of us, most of the time.
One of the many things we have embraced is the idea that we are democratic, not just in having a right to vote, but in having a right to a good life (a sort of egalitarian pluralism that we mostly believe in). While this does not always turn out to be true, as long as we continue to agitate for the right of all our people to have good lives, we are heading in the right direction.
The anthem is seen by some as uniting us, and not singing it is therefore dividing us. But the anthem is a symbol, as is not singing it. It is the ideal of everyone having a "fair go" that unites us. If not singing an anthem is one way that someone can point out an area that is important to them where they feel everyone is not getting a "fair go", then really, that is being a part of us.
I think the respect shown in this forum, in the media, by the NRL, to this idea of a protest, is also part of our united faith in the idea that we should all strive for everyone to have a good life.
It may not be a perfect protest. The criticism of it may not be perfect. But mostly it is coming from a place where we want to see all our people have a fair go.