agee was a mere case officer and knew about minerva, wrote about it in the book he published in the 70s. snowden had access to documentation for dozens or hundreds of projects, many of which were much more damaging to leak (eg technical details for xkeyscore) than a pgp attack. nsa breaks things so their analysts can decrypt intelligence. it's not much use if your people can't use it.

To further your point, even Snowden didn’t have access to the documents that tell us precisely what BULLRUN is able to do, or how.

(The speculation is, of course, with reasonable circumstantial support, is that it is a ~$1B program that has brute-forced the most common 1024 DH group in use.)

We simply don’t have the hard data, it is (educated) speculation based on what information we do have.

Even the existence of the program is TS. Its capabilities remain secret, due to the exact system you describe.