The conclusion so far on debian-legal is that the DFARS clause simply
annuls most of the extra rights that US copyright law ordinarily
grants to the government, and so is not discriminating *against* the
government.
I am not a lawyer, and I don't know for sure what the clause means.
But if it means what you say above, I think it is no problem.
As you say, it is not discriminating *against* the government.