I read what you wrote, and you made the leap from NSLs to the NSA, when it’s really the FBI that uses NSLs. Furthermore, NSLs are indeed for metadata, and not content:
National Security Letters.
Five federal statutes, in roughly the same terms, authorize federal intelligence investigators (generally the FBI) to request that communications providers, financial institutions and credit bureaus provide certain types of customer business records, including subscriber and transactional information related to Internet and telephone usage, credit reports, and financial records.37 Unlike a section 215 production order for tangible items, a national security letter (NSL) need not receive prior approval of a judge. However, NSLs are more limited in scope compared to a section 215 order, in terms of the types of information that can be obtained. For example, NSLs cannot be used to receive “content information” — the content of a telephone communication or e-mail message is unavailable through a NSL, but a NSL could request the phone number dialed or the e-mail addresses used.
The NSA doesn’t run things for the FBI, and it certainly wasn’t running PRISM for the FBI. If you would like to claim otherwise, please support your claim. And what does any of this have to do with NSLs?
And you did mention PRISM, and you mentioned it in the text I quoted (what was that about reading comments, again?). I’ll quote your reference again:
I interpreted this as you implying that PRISM was used to compromise emails (given the NSL context, which to you apparently means the NSA context) and that because the NSA was worried about other countries taking similar actions that they would not oppose encryption. If you simply meant that the NSA is going to refrain from taking any action simply because they also have other interests, then that’s something else entirely (that I would also disagree with).
Not that the NSA and its practices are really the subject of discussion here, but I suppose that’s why almost every court to have examined NSA surveillance thus far has found they are constitutional. Granted, most challenges have been concerning section 215 and the mass collection of metadata of US persons, and not section 702, but that’s likely because section 702 is even more clearly constitutional given that most of the program focuses on international communication.