The author fails to consider the fact that the US/UA codeshare predates US's entry into *A. Accordingly, it's not that they're not playing nice within the *A. The *A doesn't require carriers to codeshare on all of their flights. That's up to the respective carriers based on their business models. The non-discrimination cited with LH undoubtedly has more to do with the fact that they're not competing with one another in the domestic market where US has lots of capacity and profit margins are very slim.

One important event in the US/UA relationship is the HP/US merger. The codeshare was a pre-merger effort between US & UA when US had a much smaller left coast foot print. The combined carrier has picked up all of the HP routes where it competes more directly with UA. This is a dramatic change in circumstances. Why would US send revenue over to UA when it's got empty seats on a couple of daily flights going into the same city?

Don't get me wrong, I liked the codeshares, and I'll miss them when they're gone (just my humble prediction there, I don't know for sure that they're going). Nonetheless, as long as US and UA remain in *A together, I can still bank the miles wherever I want, and just book the desired flights thru UA's booking channels and probably save myself some minor codeshare headaches in the process.