Yes its an Australian based mailing address
If you've got any proof of residence for PNG I think you've got a strong case. Worth emailing
[email protected] to ask if changing your mailing address now would be sufficient.
If that doesn't get anywhere, you could go down the speculative route cancellation option with a classic award such as:
I'd say there's a very good chance this flight gets cancelled given Joyce's comments this week about only vaccinated travellers being able to fly on QFi. The upward spike in cases in Japan right now and significant lack of testing means there's unlikely to be a bubble on the horizon, but if a bubble were announced, I think QF would be more likely to run SYD-HND and MEL-HND flights until there's sufficient demand to justify BNE-NRT. My 2c anyway.
Assuming the flight is cancelled, you'd then be eligible for the extension based on:
If the booking is cancelled, will my status still be extended?
If you’ve made a booking in line with the requirements and Qantas cancels the flight you’ve booked, then yes we will still extend your status.
The only downside to this approach is tying up 25k points and $145 taxes until Qantas cancels the flight, then waiting 3 months for a refund.
There is a risk that the flight goes ahead, in which case you'd need to cancel it the day before departure with a penalty of 6k points. The rest of the points and taxes would still be refunded.
There may be other QFi routes which are more likely to get cancelled, this is just an example. The key seems to be finding something in April which is still bookable.