How is that a draw? But anyways I’m probably not gonna read this.
Strictly speaking, it's not; he won outright.
That said, this could be considered a preemptive technical draw. Their duel had two rules: no maiming, no killing. Had the instructor not interfered, he would have broken
at least one of the two, which would have been a ruling based loss for him.
However, the girl was also incapable of defending herself from, well,
anything he did and the instructor stepping in as she did would have been a technical knockout. Since the two results happened simultaneously, both lost, so it becomes a draw.
Beyond the technical aspects, it's essentially a way to reprimand him; "you won, but your lack of restraint has terrified everyone around you and you nearly murdered a classmate, so don't feel good about it."