In sketches from John Webber in the 1770s, both Hawaiian males and females were depicted with long and short hair. An argument could be made for or against long hair in the cultural sense as both had a place in pre-Contact Hawaiian society. For example, the cut known as 'oki mahiole is known to be a cut used for those in mourning and those who are practictioners of certain akua. Shoulder length hair or braided hair tended to be associated with Kū. The depictions of Kū and of Kanaloa tend to actually depict braids. Dyed hair, particularly reddish or white, and long flowing wavy hair tended to be associated with Pele practitioners. In a person's life, these styles tend to change. Often, due to the influence of Christianity, we tend to think that Kanaka Maoli simply stuck with one or a two akua for their life. But in actually, devotion to one akua tended to shift. Kamehameha for example was a devotee of Pele and once unification was achieved, he shifted to the mo'o sect of Kihawahine. Sometimes this shift was marked with a new haircut.
In the Hawaiian mourning cycle, cutting one's hair was highly symbolic and ritualistic. Chiefs ritually cut their hair when they lost a battle. Chiefs also ritually cut their hair in specific forms to show their mourning. ʻAko poʻo ʻōʻū (to cut off all the hair at the back of the head and leave hair only in front) was a mourning haircut often associated with chiefs who lost a child. The papa.ʻiole, an irregular "rice bowl" type of haircut, was a cut often associated with chiefs who were in mourning for comrades. The ʻoki kīkepa, cutting or shaving one side of the head, was also a ritual haircut for mourning. The ʻoki pohe or crew cut was another ritual haircut done in times of mourning. These haircuts apply to both males and females.
One of the reasons why such haircuts were attached to such mourning rituals is the time and effort it would take niho 'oki (shark tooth haircut tool), niho pūpū or niho ʻā pele (obsidian or volcanic glass haircutting tool) to have one's haircut in accordance to the mourning rituals. Hawaiians of old deeply valued effort in general and such outward displays of mourning and affection showed such efforts.
One must remember that in pre-Contact Hawaiian society, mourning was not simply a private matter of grief, but a public display of affection and loyalty complete with kanikau (wailing), temple rituals, ritualistic hair cuts, ritualistic meals, and specific kapu. It was thought that such displays of affection, ritual, and loyalty in the practical sense helped mourners in the grief process and to affirm ties of community. It can also have a cleansing and therapeutic effect, as it is still common among modern people in many different cultures today to have their hair redone after a messy break up or a traumatizing death in the family. In the Hawaiian spiritual sense, it helped the departed know that his/her life was appreciated and that it's okay for them to rejoin their ancestors in Pō.
Picture: Tikhanov's of King Kamehameha the Great (1818) sporting a cut known as the 'oki mahiole when he went into formal morning.
While some arguments through Hawaiian culture could be made for keeping the hair long or for cutting in the ʻoki huelo (short hair), I personally think that schools including Kamehameha Schools should allow Hawaiian children to either grow their hair long or to cut it because both outward expressions can be found in Hawaiian cultural norms.