OK, anons, my Caisson/Riderless Horse theory:
Just like SA gave our CINC the only Sword Dance, Japan the Feeding of the Koi, China the Forbidden City, Queenie ducking while OUR CINC inspects her troops:
The envelopes were last-minute USSS notices to the recipients that GHWB would NOT be receiving this military honor, and so new USSS arrangements had been made. W knew this, as primary protectee, and Laura and Jeb's shock was realizing the worlds' Militaries have co-signed against the House of Busch.
Welcoming critics to this theory.