I was actually wondering about the BGT requirement as I wrote that post W. Wasn't totally sure about it at the time, but figured it was better to mention a requirement that might no longer exist than ignore one that actually might exist. Like I said in the post, I'm not yet fully caught up on licensing requirements so will have to check tomorrow - unless someone comes up with the right answer in the meantime.
The days of piston-engined aircraft in PNG are probably quite severely numbered, I fear. Just to give you a bit of an idea of the current situation with Avgas, last time I was in Vanimo - just a month or so ago - a 200 litre drum of Avgas cost K1,000 from MAF. They're importing the fuel themselves and distributing it to their bases, so the cost has gone thru the roof.
There are also places where Avtur isn't available, but I think that is limited to the Highlands region. This has been the result of the refusal of fuel companies to send tankers over the very much degraded Highlands Highway, where there is risk of serious damage to, or even loss of, tanker trucks. And, of course, the local criminal element had been taking advantage of the poor road conditions to act as natural roadblocks, thereby helping them in their robberies.
I haven't been into the Highlands for a while, so don't have an up to date picture of the situation, so Avtur might again be available there. Regardless of this, aviation in PNG is nothing like it used to be and I can't see the situation improving any time soon.