First of all, Lincoln did not allow the confederates to seize federal facilities all over the south. Buchanan did that, and Lincoln was in record as opposing it. In several speeches prior to the inauguration, and in his inaugural address itself, Lincoln had stated his position that the U.S. would continue to retain those facilities belonging to it that had not already been seized by the Davis regime. And why not? Sumter was federal property, built by the federal government on land deeded to it by the South Carolina legislature, and the Davis regime had no claim to it.
He knew and understood the consequences of his actions. It was a calculated political stroke on his part.
You seem to put great emphasis on Lincoln's words as if his words alone are all the proof any student of history would need to understand that Lincoln was just trying to keep the peace. Bull! He sent that fleet into that harbor to pick a fight with an opponent that was only too eager to oblige him.