Today the government introduced a new Commerce Amendment Bill to the House, with the intention of getting it to select committee by the end of next week. While the ful text isn't up on legislation.govt.nz yet, the description on the Parliament site makes the target of the bill clear:
The primary focus of the bill is to fundamentally reform the regulatory control provisions of the Commerce Act 1986. Other amendments include imposing enhanced information disclosure regulation on certain services supplied by 3 international airport companies and providing for the enforcement of variation of undertakings given under section 69A of the Commerce Act 1986 in relation to clearance or authorisation of mergers.A point of order from Gerry Brownlee on the bill made it clear that the bill would primarily amend parts 4 and 5 of the Act, dealing with price controls and authorisations for mergers. Reading between the lines, it seems they'll be demanding international airports to justify their prices, and setting themselves up to impose price controls if e.g. a foreign owner decides to extract monopoly rents. It's a good move anyway - airports are natural monopolies and deserve tight scrutiny and proper regulation to prevent abuse. The fact that it may annoy the Canadians is just icing on the cake.