Best Māori Language Album isn't a category this year. Hill said he and Rika were unsure why the VNZMA had made the change.
Alien Weaponry and Teeks were also nominated for Best Māori Artist and were still in the running. Hill said Rika "absolutely" supported them.
Hill said he believed other Māori artists should have been nominated too, but refused to say who they were because he had not spoken to them yet.
He said the organisers of the VNZMA were supportive of Rika's decision to withdraw from the competition.
"They're right behind artist's decisions, no questions asked really."
It's the second year in a row that the New Zealand Music Awards have been involved in controversy.
Last year, R&B singer Aaradhna refused to accept her Tui for best urban/hip-hop artist, saying she was a singer not a hip-hop artist and that she felt she'd been put in a category for "brown" artists.
"This song is Brown Girl, it speaks so many things, it speaks racism, and being placed in a box. For me, I feel like if I was to accept this, I'm not being truthful (to my) song."