[Svartalfiar]

There is also the possibility that the Air Force went for a sole source contract, if they felt that only SpaceX could offer the service they need.

Well, considering that ULA launched the first 4, I highly doubt this is the case.

[exDemMom]

I do not know, I was mentioning a couple of possibilities. There is more involved to a launch than merely being able to get a vehicle into space; it is possible that ULA was not able to offer a service that SpaceX could provide.

Without having any inside knowledge, it is difficult to know what happened. We simply cannot say, based on the evidence in this article, whether ULA has a valid complaint or not.