I suspect the parent may be too busy to make a living.The parent should come up and let people know which school to add pressure. The bully should be at least suspended for years to make sure he fail his PSLE and go Northlight to continue fighting.
Sometimes they may not be good in English to challenge the principal.
In this case, since a police report has been made, the parent can choose to escalate. K shan and PM Wong are both MPs in the north.