Bismarck,
Rock and a hard place.
Torpy is an airman and would press for Tiffy. CDS is now purple and would, one hopes, consider the balancing act. For Torpy to back off on Tiffy and concede Harrier/CVF if he sincerely believes that Tiffy tranche 3 is correct would be a betrayal of the Air Force.
CDS, on the other hand, balancing the need for a balanced budget and the need to pay for tranche 3 has to make the best of what he has.
That CNS (or whoever) adopts an entrenched position opposite Torpy's is quite properly the correct blue approach for his service.
CDS thus has to opt for one or the other and just because he is light blue/purple does not disqualify him from opting for a light blue solution bitter as that may be for dark blue.
Rock and hard place.