If you have to justify the separation with a moral cause, then you don’t have a right to self governance. If I have a right to something, then I don’t need to justify exercising the right.
Complete and utter nonsense.
"When in the Course of human events, it becomes necessary for one people to dissolve the political bands which have connected them with another, and to assume among the powers of the earth, the separate and equal station to which the Laws of Nature and of Nature's God entitle them, a decent respect to the opinions of mankind requires that they should declare the causes which impel them to the separation."-- Opening lines of The Declaration of Independence
When the men who wrote and signed the Declaration of Independence also wrote their first constitution -- Articles of Confederation -- they called it a "perpetual union", they did not intend it to end in secession.
When they later wrote a new US Constitution, they changed "perpetual union" to "more perfect union", and they provided protections against rebellion, insurrection, "domestic violence", invasion and treason.
All expressed or implied that "dis-union" could only legitimately come from 1) mutual consent or 2) oppression & usurpations "having that same effect."
But neither of the Founders' legitimate reasons existed in December 1860 when Deep South Fire Eaters began the process to declare their secession, Confederacy and war on the United States.