Regardless of how useless or useful, Fort Sumter was still a Union fort manned by Union troops, one of the few in the Deep South.
Lincoln's goal was to hold Fort Sumter to bargain for something valuable, like Virginia.
As for threatening ships in Charleston, SC, that was certainly not on Lincoln's agenda in early April 1861.
DiogenesLamp: "Stopping the South from direct trade with Europe was the only thing the Fort was capable of doing, and therefore to protect the profits of those New Yorkers that controlled all such trade prior to the South declaring independence, the fort was essential as a casus belli."
If you examine a map of 1860 Southern railroads you'll see there were at least a dozen Southern ports inter-connected by the rail-net and so capable of shipping and receiving products for distribution throughout the South.
Charleston was in no way special, unique or even the largest of those Southern ports.
So whatever value Fort Sumter had, it was in no way a serious threat to the South's economy.
DiogenesLamp: "New York runs this nation today.
New York Media power elected that corrupt Chicago cretin "Barack Obama" and that disgusting corrupt con man "Bill Clinton."
Both served the interests of the New York Plutocrats who have undue influence in our government. "
But by "New York" what you really mean is: Democrats, and Democrats come from big cities in every state, especially these days from California -- San Francisco, Silicone Valley, Hollywood, etc.
On this map, blue marks the home of your "New York Power Brokers":
Note that some of your "New York Power Brokers" even live in the Deep South!