Having a "right to rebel" does not suppress or negate others from possessing an equal or superior right to defend against that rebellion.
Those are your words, not Lincoln's. Lincoln didn't say anything about tyranny being a prerequisite to forming a new government. He said, "Any people anywhere, being inclined and having the power, have the right to rise up and shake off the existing government and form a new one that suits them better."
He further stated, "Nor is this right confined to cases in which the whole people of an existing government may choose to exercise it. Any portion of such people that can, may revolutionize, and make their own, of so much of their territory as they inhabit."
In addition, your brazen attempt at revisionism falls flat on it's face. The election of Lincoln in 1860 insured that 1) a tyrant would takeover the government and 2) the South possessed all the wherewithal they needed to form their own government, which is a historical fact. At least until the day when you revisionists are completely successful in eliminating all vestiges of The Confederate States of America.
Having a "right to rebel" does not suppress or negate others from possessing an equal or superior right to defend against that rebellion.
Lincoln's government was not on the defensive since Southern secession clearly did not have as a goal to abolish the yankee government. If the goal of Southern secession was to topple the Lincoln regime then DisHonest Abe would have been obligated to defend against that.
Try sticking with the facts and forget about your fantasies.