I have to agree really.
Sure, it's nice to show pride in your culture by adopting a traditional hairstyle, but it's not exactly a religious/cultural requirement of your heritage, so you should have considered your school policy first.
It's not like a Sikh being reprimanded for wearing a turban.
Well it's apart of their life style, its a stupid standard that serves no other purpose other than just because.
It would be like getting conquered by the Romans. You can look, act, or do as you did before being conquered as you are now required to look, act, dress like a roman and do roman stuff. Such is imperialism.