The key piece of information is the treaties. Long story short: The treaties a were signed with “the Crown”, the absolute power of Canada that still exists (it’s just no longer controlled by the actual Kng but by the government) with the sovereign first nations.
This is a small distinction but it makes all the difference. The treaties supercede any other Canadian legislation because they are signed with the Crown itself, the representation of the full abstract authority of the government, so they outweigh (at least in theory) any other law that came after.
The chiefs are calling the King as a power move, they are reminding him and the Canadian bureaucrsts “your ancestors and descendants are bound by this deal, the power you represent is bound by this deal, it is not a negotiation”
Imagine pulling an email with the CEO while talking to a manager, this is what they are doing.
Lol why don’t you touch some grass?