She should get the principal's response in writing and take his negligent behavior to the school board. I suppose negligence is "cultural" too.
He knows better than to write it. Using a tape recorder is preferred but watch out. If you pull one out at a school board meeting to play the words of an administrator, they'll react as if you pulled out a hand grenade.
Nothing upsets people more than hearing something they are trying not to hear.
She tried, nothing happened- unfortunately in this case a majority of the school board shares the same ethnic background and desire for excuses as does the principal.