Jeff I think you're getting confused with FIFA eligibility regulations and A-League local player regulations. If Ifill already holds a NZ passport he would already be classed as a local player.
To be classed as a local player for the Nix in the A-League a player simply needs to be a citizen of NZ or Australia. It just so happens that you need 5 year's residence in NZ to apply for citizenship (in normal circumstances).