The Napier parents contacted the show to air their side of the story.
Lucan's mother Tania Doidge said they had a responsibility to support their son.
"You have got to stick to rules and boundaries, but you also have got to support your children when they are trying to stand up for something that is important to them," she said.
Lucan, aged 16, said his exclusion was unfair because his hair was "tidy enough".
Previously he complied with school requests to cut his curly locks, but now wants to tie them back.
The Hastings Catholic school for boys' policy on hair is it should be short, tidy and of natural colour.
Father Troy Battison, who sports dreadlocks past his shoulders, said after a 30-minute meeting last week Lucan was suspended for "continual disobedience that is a harmful or dangerous example to other students."
He said the school was being inconsistent because there was a teacher at the school with longer hair, who wore it tied back.
"If Lucan is setting a dangerous and bad example, would the teacher not be doing the same?" Mr Battison said.
One-on-one meetings with school principal Paul Melloy and the school counsellor did not resolve the matter.
"Once the board basically backed the principal - wouldn't let him tie his hair back - going to the High Court was the only avenue. We couldn't go anywhere else - they refused mediation."
The parents have sought a High Court review of the school's decision, to be heard on Monday.
Mr Battison said he knew the majority of public opinion would be against their High Court move.
"This is one of those classic cases of the only person who are going to win are the lawyers."
Mr Hosking was unmoved by the parent's response to his criticism.
"The simple message in life is what? When you go to school you follow the rules," Mr Hosking said.
"That's what you learn at school, that's how you learn to be a functioning member of the community."
Lucan told the show he was not enjoying his suspension.
"I feel like I've got no motivation to do anything. It sucks being away from rugby as well," he said.