I think its more to do with the perceptive (rightly or wrongly) that no matter how much gas they find - they won't be able to compete with alternatives.
i.e. Future suitors such as BG, Shell etc won't want to touch SXY because they fear future US supplies coming online and it being cheaper to import the gas to Australia.
Much depends on where the value of the AUD goes in future years & if the US congress allows their gas glut to be exported rather than benefit local consumption/manufacturing.
IMO I don't think the US will allow large scale export of their gas, as it would reduce the edge it gives local manufacturers and also creates political problems with allies such as Qatar.
SXY Price at posting:
57.7¢ Sentiment: LT Buy Disclosure: Held