I find this quite plausible, with or without the knowledge of Page, Zuckerberg et al. the NSA might very well have the private keys of these companies. I would not be surprised if the CEO's of these companies choose to be ignorant of the NSA's methods to not have to lie to the public, shareholds and Congress.

Also, given that the world's best engineers work at either high-tech companies or the NSA there will be some who have switched between these industries, giving the NSA/CIA a headstart to get any information these companies hold through old-fashioned spy-tactics.