Oh yes, they were indeed, however the Maori are really outstanding in this ~ even among other Polynesian cultures. They will be predominately focused on military if we get the Maori.Pre-colonial Polynesian nations as "cultural civs" by Civ6 reckoning is a very modern, historiographical viewpoint. Historically, in truth, the Polynesians, while they had a lot of ceremony around their religions and monarchies (but didn't most civilizations back then, in truth?) were indeed VERY well known as fierce, frightening warriors, aggressive, fearless explorers, and very pushy, belligerent traders - a reputation almost akin to South Seas Vikings - and that was almost across the board except maybe the much latter-day Tahitians and Hawaiians.
If that is what you want in the Polynesian civ, then by all means vote for the Maori...And personally I would hope that we get more than one Polynesian civ, and get the Maori as well as some other civ (like Tonga or Hawaii), so we can get representation of more of Polynesian culture as a whole. As I think that most likely we are only going to get one Polynesian culture, I am more focused elsewhere, as I have certain things I want to see in the Polynesian civ, one of which being that they are not too focused on military. I don't think military should be neglected, don't get me wrong, but at the same time I don't want the main focus to be on that either. Pre-colonial Polynesia was rich in culture too, but at any rate, the game goes through history and plays through every age, so it would not be unusual or unhistorical for Polynesia to get more modern cultural benefits.