In my opinion the reenforcements carried by the "Star of the West" were intended to blockade the port of Charlestown Harbor and isolate the city as Winfield Scott did under Andrew Jackson, sending in reenforcements to Fort Moultrie in 1832. Remember that Winfield Scott was a close associate of Lincoln's and had been for several years in reorganizing the old Whig Party into the Republican Party.

However when the mission failed and the "Star of the West" abandoned the attempt the whole plan backfired and within weeks six other southern states seceeded, which did not happen in 1832. That meant that Charleston and South Carolina was no longer alone and could no longer be simply isolated.

No sooner that Lincoln was sworn in as President on March 4th than a larger relief force was organized, and the plan revised. This time it's objective was to goad the Confederacy to either fire on Fort Sumter or the relief fleet it did not make any difference which one to Lincoln. The only reason why the war didn't start with the "Star of the West" was because Buchannan, although a lame duck, was still President in January and did not act upon that provocation at that time.