“But on land deeded to the federal government free and clear by act of the South Carolina legislature. Why shouldn’t the government have a right to resupply it?”
Because due to the power of Eminent Domain, South Carolina claims it. So it wasn’t federal any more nor was any other federal installation in a sovereign state which had seceded.
You just make crap up as you go along, don't you? Eminent domain doesn't allow states to seize federal property any more than it allows the federal government to seize state property.