Then you will argue that point with yourself.
Because there is no arguement you can possibly offer to support your case. No rule of law, no precedent, nothing to cover what those actions were, out-and-out theft of property. Sumter was the property of the federal government, built on land deeded to it free and clear by the South Carolina legislature. The state had absolutely no legal claim to it, and even if you want to offer your lame excuse that property of the federal government was really property of the states then that would still mean that it was property of ALL the states. And for South Carolina to seize it without compensation would still be illegal.