He does have a point. If James Buchanan had been as decisive as Andrew Jackson was the last time South Carolina talked of succession, and threaten to send the Army to hang all the secessionist, it might have averted the civil war.
Instead he did nothing for awhile then finally made a spineless announcement that the states had no right to secede but the federal government had no right to force them to stay in the union. Then handed the whole mess to Lincoln and scurried on home.
Or might have provoked it earlier. The Southern states were firm in their intent to leave the Union after Lincoln's election. There was nothing wishy-washy about their actions or their motivation of defense of slavery. A threat to resort to military force would not have caused them to back down. It would have resulted in the South calling up their own troops and the war beginning a few months earlier than it did.