Perhaps some day
but right now, most of the NMD system that I've seen is ground based. At least in the initial architecture, the only parts of NMD that would be space-based are the SBIR satellites. I doubt we'll contract out those launches. Now, some time in the future there could be space-based lasers and other more exotic systems so your idea could have potential, especially since we're trying to sell Russia on the idea that defense is a good thing.