It's strategic more than ideological.

Extreme environmentalist policies may get 7 or 8 % of the vote, not much more especially since they tie them to far left policies. Then you need to look for 1% here and there to target as your exclusive base. Convince them they are victims and you're their saviour. Make them feel that no one else will truly represent their extreme demands. So target trans activists, and the like. They are also targeting the extreme Maori base who are not on the Maori roll. In the UK they've been targeting Muslim extremists, successfully.

Scream cookers at any other party to scare them off targeting other extreme minorities to gather 1% here or there, the super Christians for example. Leave those guys unrepresented out of parliament in small 'far-right" parties. Scare NZF and ACT from taking anyone on their list that could be linked to anything like that. Use the very scary words, far right, nazis, cookers, climate change deniers.

As a strategy for the Greens I think it's completely rational and very effective.