Yes, parents have the right to make medical decisions on behalf of their minor children. Are these decisions sometimes terrible decisions (in the opinion of others)? Yes. But some parents also physically and sexually abuse their children. And until they get caught and stopped, they continue to do so.
What's fascinating about this sad case is that Canadian settler judgement and the colonial ("We know what's best for you") mindset sure are selective when deciding what is and isn't a "horrible problem" in the Aboriginal community.
No potable water? Yawn.
High rates of suicide in remote communities? Whatevs.
Mouldy trailers for housing? Who gives a shit.
Schools and community centres in need of drastic repairs? Clearly they have mis-managed their community and need no intervention.
An individual family making a medical decision about their child? However much anyone inside or outside the community approves or disapproves? Oh My God, sound the alarm! Alert the media! Go to court! Crisis! Crisis!
In this case, having settlers, with their/our colonial mindsets, bicker over a single issue, a single example, is very typical, historical, hypocritical and pretty gross.