Different command chain = bingo! The number of operational awards at each level is capped (the number adjusted for each list depending on what level of activity there has been) and awarding a DSO to a JHF(A) Cdr would have meant one less regimental CO getting one. Given that the sifting between those 2 alternatives would have been under the Land chain, you’ve answered your own question. The stray Harrier nomination would have arrived at the Joint board via the Air chain of command and would probably have been horse-traded into the final list in exchange for the Air commanders’ full support for all the other awards. It is that kind of process, sadly...