South Carolina's Ordinance of Secession was passed on December 10, 1865 and Her Declaration of Causes on December 24, 1861. There is no editing going on.
Secession was undertaken to defend slavery. The Confederacy was a defense of slavery. Its whole purpose was to defend slavery. Secession and the Confederacy had no other purpose. No slavery = no secession = no Confederacy.
You still ignore the states which seceded due to Lincoln's demand for troops. Why?
I agree that history isn't pretty. Yet who is looking back, who is having a ball to commemorate the anniversary of secession, i.e. to commemorate slavery? If you want a curtain drawn over the past then you'd better draw it over the past. Some people want the right to remember the past they want to remember, but to forbid the right to remember the past to others. How convenient.
I don't see South Carolina drawing a curtain over anything. Has she ever denied slavery? Nope. It appears you are the one that only remembers the past as you want to remember. The North was more sinner than saint. When you are pointing a finger at someone, there are always three pointing right back at you.
Correction: Should read December 20, 1865 NOT December 10, 1865.