The fact that decisions of the Waitangi Tribunal are not binding on Parliament and Government is not a great surprise. In fact not even the Supreme Court of New Zealand can bind the New Zealand Parliament. In the absence of a written constitution, we live in a democracy where Parliament is supreme.
John Key is not the first Prime Minister to make clear that a policy which has been ratified by legislation in Parliament, will proceed regardless of what the Waitangi Tribunal says. Helen Clark in 2000 said " the Government's settlements were based on policy, not Waitangi Tribunal recommendations". Her associate energy minister even said "he had assured oil drilling companies of continuing crown ownership of oil and petrol - and no Waitangi Tribunal hearing or subsequent court action by Maori would change that."
So a statement by John Key that the view of the Crown is that no one owns the water, the sea, the air or the airways is normally quite unexceptional. But in politics, timing is everything. The comments were made, in response to a question, on the day the Waitangi Tribunal was meeting to hear a claim over the part-sales of the power companies, and their potential impact on Iwi claims to water rights.
Many in Maoridom, including the Maori Party, saw it as implying that the Waitangi Tribunal would be ignored, regardless of what they may say, and how well they justified their decision. There is a difference between saying "We don't have to take their advice" and "We will ignore them". The Prime Minister says he meant the former, but many heard it as the latter.
This means there are some tensions to be smoothed between the Maori Party and the Government in the next few days. No one should expect the Maori Party to walk out of having an influence on Government policy, because of the way the Prime Minister answered a question.