Is he saying that just because he can't get a start in the Australian team? This is why the IRLF need to have some solid rules.
My two bob:
Origin (and Australia) can take a hit of having a few blokes unavailable if it means international comp is stronger. The NRL/IRLF just need to make internationals more attractive to players like Costigan and Hayne (maybe with game "Ambasador" money to make it more lucrative outside of the NRL cap, like the Aboriginal or Origin "ambasador" money in the NRL).
If they still want to play origin and for Australia, great, but once they pick one way or the other there should be NO switching...
They do have solid rules.
He is eligible for PNG only, because he played for PNG. If he wants, he can apply to be eligible for another country once in a world cup cycle, so until he actually plays for Australia, he is eligible for PNG.
Origin (quite rightly) has zero effect on international eligibility, because it is solely an ARL run concept. I hope costigan sticks with PNG and forces the ARL's hand in selecting him, like Adrian Lam did, when the ARL had arroganltly assumed he would play for Australia before PNG.