OP, where did you see Blizzard Directly say they lost 600,000 subscribers? In WoW Insider, the Blizzard rep stated a loss of "subscription levels" which can easily mean total subscriptions/subscribers. This does not say anything about the 12million subscribers being the same people, but instead that they "now" have 11.4million subscribers. In previous statements they even addressed what a "subscriber is" and how there can be less people involved than the "subscriber" total.
I do not see a lie here, merely a misinterpretation caused by poor reading comprehension.