In fact, I'd go further. That these pundits aren't even discussing the real oath CIA and other government employees take -- the one to protect and defend the Constitution against all enemies, foreign and domestic -- suggests they don't believe such oaths are important enough to bother mentioning. Now, admittedly oaths to protect and defend the Constitution are all very pre-9/11, but shouldn't an intelligent and honest pundit at least offer a nod of the head toward the fact that someone like Edward Snowden might have felt faced with two competing obligations -- his secrecy contract, on the one hand, and his sworn oath to protect and defend the Constitution, on the other?
Of course, if deference to governmental secrecy prerogatives trumps all other values, then there's no trade-off even to mention.
And look, even if you think that "oath" and "contract" are interchangeable terms (in which case you'd have to explain why Brooks, Marshall et al consistently use the former regarding secrecy while eschewing the latter, and why the drafters of the Constitution did the same with regard to oaths of office), you still have to explain why various pundits are so intent on referring to only one of the "oaths" while ignoring the other.
Here's another way of looking at it. Say you're the employee of an intelligence agency. You've signed a contract to maintain secrecy and also sworn an oath to protect and defend the Constitution. And you become aware of a secret program that you believe violates the Constitution you have sworn to protect and defend. Reasonable people can argue about how you might best redress that violation, but reasonable people can't deny, whether explicitly or implicitly, that you are faced with a dilemma and that, if you have a conscience, you should and hopefully will grapple with how to resolve it.
Here's a terrific piece from Daniel Ellsberg, the previous generation's heroic whistleblower, on why in revealing the scale of the NSA's secret spying on millions of innocent Americans, Snowden has done America such a noble service.