But that's just a mechanism for the corruption. The contract for the design of something and its manufacture and maintenance should each be separate bids. Even each stage of the design should be a separate contract that could go to someone else. The government says "we need a design for a ship" and they put it out to firms who submit their proposals and then the government picks one and buys it outright. Then they say "we need a design for a propulsion system for this ship" and take bids again. If you need to modify the ship's design some to facilitate it, that's fine, because none have been built yet and the necessary change gets incorporated into the design before you put out contracts to build any of it.
What you want is for each of the contracts to be as small as practicable, to maximize the number of potential bidders. None of this "single contract to design and build an entire fleet of ships and maintain them for 30 years" nonsense.
Claims that you can increase the efficiency of a system by reducing competition should be met with the same level of skepticism as claims that you can violate of the second law of thermodynamics.
But let's try one that should get their ears to perk up. Monopoly suppliers are systemic risk, which is a threat to national security.
Yes, we should reduce corruption and break up existing entrenched players, but the core issue is in the structure of that kind of arrangement. I do also think that there's no good reason to have a "corporate veil" in the first place, but that's a broader problem