Well, admittedly, I haven't been following this as closely as I had been but, the last I knew about the 2 people in that report was that they weren't on the Citation. The story I got was that they'd arrived legitimately in Port Moresby and travelled to Buka on a domestic F28 service (ie again a legitimate form of travel).
From there, they went by boat to Bougainville and, allegedly, entered the "No Go" area on the pretext of installing or repairing satellite TV dishes. Well, something like that anyway...