If the government says, "Give us $X so that we may use it to purchase a health plan that includes contraceptive coverage," the effect is exactly the same as if they said, "Spend $X purchasing a health plan that includes contraceptive coverage." I don't see how one could be moral and the other not.
I can see it at the point where it changes from spending money to taking actions. Actually dispensing or taking contraceptives would be qualitatively different from paying for a health plan. But if it's just your money going to an insurance company, I don't see why it matters if it passes through the government first.