The federal acquisition regulations have fairly strict rules against acquiring duplicate systems. It totally permits buying systems from multiple vendors, but there are interoperability requirements, and these would have to be interpreted and negotiated. If Kuiper wants to provide services to the government, I’d expect that they would have to be compatible with the Starshield user equipment at a minimum. The military doesn’t want to be lugging around multiple satellite terminals to connect to both the SpaceX and Kuiper versions of Starshield. I doubt the government would go so far as to require SpaceX and Kuiper make their constellations interoperable in space, but even just requiring compatibility with the ground terminals is a pretty big hurdle.

SpaceX has proprietary info in practically all of their comm layers, so interoperability is not easy. The government probably did not buy full rights to the protocols. So the first step to Kuiper getting a piece of the pie is convincing the government that it is worth paying to license SpaceX’s comm standards so Kuiper can use them. That is not an easy task.

There are a dozen hypothetical ways that Kuiper might get a portion of government programs, but the fact is that SpaceX has been embedding themselves into the US government’s space infrastructure for years without competition, and has used that lack of competition to build up a bunch of technical hurdles to purchasing services from other contractors. For the past several years there has been no reason for the government to spend money and effort to prevent these hurdles because there was no other contractor that might be able to offer a similar service. So SpaceX has got a pretty sweet position right now, and Kuiper is going to have to invest heavily before the government changes course.