Well you would be right in terms of this working but if the NSA were doing this it would have been noticed. Also, that trick won't work when certificate pinning

Well you would be right in terms of this working but if the NSA were doing this it would have been noticed. Also, that trick won't work when certificate pinning gets involved so going to Gmail in Chrome would pop up a warning message if they tried. Supposedly PRISM has access to Gmail so at the very least the NSA is doing something else in addition to selective SSL MITM attacks.