The student handbook may grant authority for searches beyond what are otherwise allowed under law, but do not otherwise restrict searches. If the school had a reasonable basis to conduct the search, the handbook is irrelevant. Schools have relatively broad authority to perform searches in order to ensure student safety.
The student and his parent can discuss the situation in detail with a criminal defense lawyer, but they should not be surprised if the lawyer concludes that the drugs are going to be admissible in court.

