> You're assuming it requires specialized military gear, as opposed to consumer gear with a flashed firmware.
The author studied this supposition [code intended for mil gear] for some time and learned this.
On 26 May 2011, all 31 active GPS satellites switched to the
0xAA placeholder within just a few hours.
This rapid daily change perfectly matches the operational
rollout of the U.S. Over-the-Air Distribution (OTAD) network.
That doesn't really answer the question of whether it could be used to deliver "numbers station" type messages. Encrypted key material and enciphered messages should be indistinguishable. There are 18 bytes of high-entropy ciphertext that could be used for both purposes.
The author studied this supposition [code intended for mil gear] for some time and learned this.