let's get back to the rules for a second. He has a nz passport as well as the "close connection to nz" requirement. He is a citizen and is not dependent on residence. He is eligible and this will be overturned. My balls my word.
There is no way you need to be in a country 5 years after 18, no way at all.
If you say the rules have been misread then point to the rules he would be eligible under