I think most of your point wrt the relative value of the prime Surat permits BG acquired is valid, and your conclusion that BG wont bid on the basis of that probably fair conclusion.
However, I'd say to extent that to almost saying that AOE's Bowen Basin permits are near worthless is going too far. Seems to me that completion techniques are at the point where the best Bowen gas is producible with quite attractive economics.
I'd suggest that if Shell were only interested in the Surat permits, then the deal might have been structured that way. Above all I really don't think Shell is attempting to buy a lemon just because it is cheap.
There are many things that to me point to the "BG employee" sentiments you note being essentially "fair", AND yet there being enormous future value in AOEs reserves (and resource). The "BG employee" view might be a bit like a Saudi dismissing the Bass Strait oil fields.
EL
AOE Price at posting:
$5.17 Sentiment: Hold Disclosure: Held