Even a parallel construction has limited uses, since you can't use the same excuse every time. The NSA probably doesn't trust the FBI to come up with something plausible.
>>chucka+(OP)
That depends on how apathetic people are. Most of the time they will accept a completely garbage story and you can create infinitely many of those.
>>ddtayl+w95
Sure, and that’s why juries buy the same line from cops every time, but major actors actually affected by potential backdoors are likely to be a bit more skeptical and start digging around for the real reasons.