No, the confederacy bombarded the fort, won that particular battle, but then lost their war. Not overly bright of them, was it?
The fort COULD have threatened shipping at anytime.
But it never did. All the time Anderson and his men were in the fort and not once did they halt shipping, not once did they threaten the town, not once did they take any hostile action whatsoever.
The fact that they didn't fire upon shipping, given Lincoln's behavior, doesn't mean a thing. They were a threat.