The child is native and therefore having long hair is not simply a fashion statement but rather something tied to the child’s culture. Cutting off the hair of male native children was regularly done at residential schools, where the goal was to “kill the indian and save the child“.

"If a First Nations teacher had taken the same actions with a non-native child, there would have been a swift and strong response," Falconer said. "The Crown attorney wouldn't be confused about the definition of consent and those non-native children would have been deemed worthy of protection.

"The message here is that First Nations children are somehow less worthy of protection than non-native children."

Falconer said the parents had come to the school in the fall after the same teacher's aide ridiculed their older son, who also keeps his hair long. They explained that the boys wear their hair long in order to participate in ceremonial First Nations' dancing.

In analyzing the individual parts of the Declaration, we see that all new rules of customary international law, as found in our respective surveys of state and international practice of 1999, 2001, and 2004, still remain part of the global consensus. As stated in 1999, “indigenous peoples are entitled to maintain and develop their distinct cultural identity, their spirituality, their language, and their traditional ways of life.” Most of the provisions of the Declaration go to the preservation of culture, language, religion, and identity; and state practice in the states with indigenous peoples largely conforms to these legal tenets. Due to the strength of the indigenous renascence throughout the world, the original goal of assimilation of indigenous cultures into the maelstrom of the modern world has largely been abandoned in favor of preservation and reinvigoration of indigenous cultures, languages and religions. The legal guarantees of these claims are, however, not the real bones of contention.

Source
The original draft of the 1948 Convention on the Prevention and Punishment of the Crime of Genocide, prepared by the United Nations (UN) Secretariat and based on the work of Lemkin, included definitions of physical genocide, biological genocide, and cultural genocide. The latter was defined as follows:
Destroying the specific characteristics of the group by:

• (a) forcible transfer of children to another human group; or

• (b) forced and systematic exile of individuals representing the culture of a group; or

• (c) prohibition of the use of the national language even in private intercourse; or

• (d) systematic destruction of books printed in the national language or of religious works or prohibition of new publications; or

• (e) systematic destruction of historical or religious monuments or their diversion to alien uses, destruction or dispersion of documents and objects of historical, artistic, or religious value and of objects used in religious worship.

Falconer said the parents had come to the school in the fall after the same teacher's aide ridiculed their older son, who also keeps his hair long. They explained that the boys wear their hair long in order to participate in ceremonial First Nations' dancing.

Newcomb: Dehumanization in U.S. Indian Law and Policy

The dehumanization of our Indian peoples has been manifested in many ways. The countless massacres, the forced removals, the boarding schools that tore Indian children away from their extended families, communities and nations, the sterilizations of Indian women in IHS hospitals in the 1970s, the attack on our languages, on our spiritual and ceremonial traditions, on our sacred places. These are just a few examples of the ways in which we have been continuously dehumanized by the United States.

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Why weren’t Indian peoples considered to have human rights? Simple; they weren’t considered fully human. Upon reflection, dehumanization is what made the UN Declaration on the Rights of Indigenous Peoples imperative. Its adoption by the United Nations General Assembly on Sept. 13, 2007, was a long-awaited endorsement of the fundamental human rights of indigenous peoples. It was the result of decades of work to put an end to the dehumanization of indigenous nations and peoples globally. Passage of that document sends the message that because indigenous peoples are fully human we possess and have always possessed fundamental human rights, including the collective right of self-determination, despite centuries of being regarded and treated as not fully human.