It's not useful scrounging up, uh, conspiracy theories for how it happened unless there is evidence.
The only argument you're invoking is abduction - that no other approach fits the facts. But the thing about the NSA is the level of spying and power that's demonstrated gives a strong indication they just don't have much reason to care what the public thinks. The average NSA bureaucrat isn't worried about the public at all but what argument their boss or colleague will use against them. And letting out information goes so hard against the default impulse that letting information out intentionally seems way unlikely, even as part of a clever master plan. I mean, if we're wandering to wild speculation land, the NSA has dozens of potential master plans. One that releases information and makes them look bad wouldn't do well in the "master-plan competition" - held yearly at Area 51!
Why would Obama sanction deeply-embarrassing revelations and expose the staggering depth of warrantless spying?
This is almost certainly not the case, but that's the answer that came to mind when you asked the question.
That being said, I'd be surprised if that were the case here. But a man can hope.
I still think it is extraordinarily unlikely though.