So a nz passenger queried for a refund for an ex NZ to US flight under DOT regs and got told a refund under DOT regs only applies to US citizens and flights booked in the US. They went on to advise in regulation 15.5 it states this.

I'm yet to locate reg 15.5 but perhaps someone might be more familiar and able to confirm if DOT regs apply to US citizens and flights booked in the US only.....that is the line NZ are taking at the moment anyway.

Will do some more research and wait and see if they change their tune.