What's to "discuss"? There is nothing in DL's response which DL has not said quite publicly in its 10-Q's and Investor calls for quite some time and which also isn't visibly apparent from its pricing.
While it's derisively referred to as FCM on FT, most call it "running a for-profit business profitably."
Bottom line here is that DL prices domestic F at quite reasonable prices and people are purchasing those seats. Thus, they aren't left over to be given away as freebies. As there are people willing to pay for those seats, even a little, why on earth would DL give them away?
You should expect the free UG to remain out there as a possibility. But, it will likely become more and more rare, even for Diamonds.