Woah guys, the title of the article is more than a little misleading. Arpey never actually said that Qantas was not a premium airline, he just didn't mention them while talking about the other oneworld carriers. That little omission has been taken by the author to the extreme methinks.
I could imagine AA wanting to expand its network to fly to Australia, and in the joint venture arrangement with QF both partners win. For AA, they have an advantage in that they can pick up US gov't traffic between Australia and the US due to their weird rules, while QF will simply add their code to an AA operated service and also potentially get upside on their domestic network.