Ann: Change in substantial holding from MIN, page-38

You are confusing the 75% for a special resolution to be passed with the 75% shares owned by one holder to apply for delisting.
Two separate things.
Delisting of a public company is under the ASX rules.
From my very quick reading, it will be MIN who apply to delist NWE, not the NWE BOD.

Can't cut and paste the PDF but for anyone concerned about delisting it is worth reading.

Guidance Note 33 - Removal of Entities from the ASX Official Lisl
2.7 - 2.12