I'm getting less interested in responding to you. You are trying to sell the idea that abandoning Ft. Sumter was a good negotiating tactic on the one hand, but a Rubicon on the other. "Principles" as I understand the word, are not so flexible. When they are so flexible, they are not principles.
From my perspective, you seem to be flailing and pinwheeling, and I think i'm just as well off to get out of the way and let you. :)
Whether Lincoln maintained troops in Fort Sumter, or abandoning the post, was not a "principle", it was a tactic in support of a great principle: preserving the Union.
The "Rubicon" was Confederates' military assault on United States troops in Fort Sumter, just as was, for example, the Japanese attack on Pearl Harbor.
Preserving the Union was the great principle against which Lincoln judged all his actions, from defending Fort Sumter to freeing slaves under Union Army control.
How you can get so much obvious pleasure from distorting and mocking that, I'll never understand.