Why not? No matter how small, as a tax-payer, I helped fund that development. National security, it is not. Should qualify as public domain.
Tax money touching development makes everything public no more than a touch of private money turns everything private. Each case is determined by the contracts signed to leverage these investments.
https://en.wikipedia.org/wiki/Copyright_status_of_works_by_t...
And copyright is not the only form of legal protection available to code.
This approach fails on all fronts.