Federal installations and federal property on the sovereign territory of a state reverted to the state when they seceded. You will note that British forts had to be surrendered to the colonies when they seceded.
Where did that claim come from? Federal property can be justly seized under no claim of state sovereignty.
It is nothing but theft.
British forts in the West did not automatically become ours and some were held after the Peace Treaty.
Though the comment is irrelevant.