On a technical note, I would have thought that Fortezza and/or CAPSTONE used some sort of hardware RNG, i.e. noisy Zener diodes or whatever. I've seen it mentioned on this list that some other NSA secure phones, such as STU-III, do that.
I was under the impression that a seed for the RNG is loaded into the Fortezza at initialization time. This would make me think that they are using a cryptographically strong PRNG. This would give data that appears random, but is completely determined by the initial state. I suspect that the "seed keys" provided by the two agencies used to program the Clipper chips has the same properties. This makes the question about how does the NSA get access to the key escrow database moot. They don't need access. They know a priori all the unit keys.