Well everyone knew they were going to be resisted. Lincoln knew it. His cabinet knew it. Major Anderson knew it, so let's move past the point of wondering if they were going to be resisted and move straight to the "What were they going to do?"
More importantly, what did the Confederates believe they were going to do? What was the impression that Lincoln wanted the Confederates to believe?
Davis ordered Beauregard to reduce the fort by force if necessary before the resupply mission arrived. Beauregard followed those orders, Anderson would not surrender the Fort. Beauregard order his artillery to open fire. Will gladly listen to what your insight, supported by something more substantial that your opinion, into Jefferson Davis believed they were going to do.