They've presumably got a pretty vested interest in making sure most communications are legitimately secure against most common attacks - arguably good for national security overall, but doubly good for making sure that if anyone can find a novel way in, its them, and not any of their adversarial peers.

There's a reason many corporate information security programs don't go overboard with mitigations for targeted, persistent, nation-state level attacks. Security is a set of compromises, and we've seen time and time again in industry that this sort of agency doesn't need to break your encryption to get what they need.