Pretty much what I was saying, but you stated it more succinctly.
I do see one difference in that going to college or getting a job isn’t directly working as an activist to represent his people, though arguably any positive actions are de facto representative. And if it was a non-aboriginal who made the symbol it would be cultural appropriation, but since he is an aboriginal, it’s his culture and he’s got no less moral right to represent it than an aboriginal business, and it’s especially not the place of non-aboriginals to tell him he doesn’t.
Anyway, I may be wrong about this, but I get some sense that people are unsympathetic to him because he’s making money off his representation of his cultural heritage. But as far as I can tell he’s using that income to fund a life of activism, which seems no less laudable than a for-profit charity whose accounting isn’t public. In fact the main material difference seems to be that he created the design and they didn’t, and they resent or are at least trying to use resentment of him licensing to a non-aboriginal company.