If that's exactly what the agent said, they were incorrect (unless they've changed the rules). See the sticky at the top of the thread for the link to NZ's published rules, which should apply to all airlines that sell the pass (prices vary of course).

Or, I'll just post the link here. It says the only points of stopover or transit in the US/Canada that are allowed are clearly stated to be LAX/SFO/HNL/SEA/YVR.

So as long as you were obeying all of the other rules (i.e. you weren't going from HNL to YVR to somewhere back in the US, you were within the rules for the # of stopovers and # of stopovers within the US, and the mileage restrictions), you should be able to book a flight to/through HNL on the pass.