Why HMS New Zealand was difficult to preserve

Could New Zealand have preserved the battlecruiser HMS New Zealand?

Yes, but only if New Zealand funded her and the naval treaties allowed the hull to be retained.

The answer treats preservation as a political and legal choice rather than a technical impossibility. New Zealand could have kept the ship if its government was willing to pay the continuing cost. The interwar treaty system also had to permit the hull to remain instead of counting it against restricted naval strength. Her ambiguous status as both a British warship and a ship closely identified with New Zealand complicated who would assume responsibility for saving her.