"In light of the significant investments we've made in talking about improving out aircraft, . . ."
If DL had said that no medallion upgrades were available on flights that actually had the lie-flats they claim are the reason for loss of upgrades, that would have been a lot more reasonable.
Now I'll bet the "don't call me a Delta-apologist"s will come up with some reason why the upgrades should be denied despite the underlying claimed reason being false.