Last week, John Key damaged relations with his coalition partner the Māori Party by threatening to ignore the waitangi Tribunal if it upheld claims to water. This week, he's gone further by calling the entire claim "opportunistic". But apart from being a nasty example of dog-whistle politics, it also shows Key's ignorance on the matter.
Water has been the big sleeper issue in the Waitangi claims process, but its been able to be put off precisely because public policy has assumed that no-one has owned it, while giving Māori a strong role in management through the RMA. That policy is slowly being reversed, with pressure over allocation, particularly in the South Island, pushing the government towards reversing that policy in favour of a system of tradeable water rights. But progress has been slow precisely because all the bodies involved (DoC, MfE, MPI, TPK, MED, LINZ, and the Land and Water Forum) have recognised that the Treaty issue needed to be sorted out first, and that if the government started selling water (even in the form of usage rights), Māori would need to take steps through the Waitangi Tribunal and courts to protect their rights (and New Zealand Māori Council v. Attorney-General (1987) gives a good idea of how such a case would turn out).
...which is exactly what is happening now. The government is selling water, in the form of hundreds of millions of dollars worth of usage rights for Mighty River Power's hydro stations. It is doing this without having sorted out that water's real ownership. So Māori are having to go to the Waitangi Tribunal - and if necessary, the courts - to protect their interests in that water. It's no more "opportunistic" than trying to prevent a fraudster from selling your house out from under you.
And that's the real metaphor we should be looking at: the government is selling something which may not belong to it. It is entirely appropriate that the real owners be able to test their ownership, and halt the sale until that ownership is determined.