Came back just to say: if there is a later flight from your origin that would arrive into AUH in time to connect to your Australia flight with a waiting time of less than 8 hours, this, too, would invalidate your claim to STPC.

Or at least, I expect that booking an "earlier" flight to get to AUH has the same effect as booking a "later" flight onwards from AUH - so the "unnecessary lengthening" of your stopover in AUH could arise based on which of several daily flights you take from your origin, too.