I don't know, but what does that have to do with anything? Had the Confederacy coupled its secession with emancipation, the war by the North would have collapsed. The South was not willing to end slavery at that time, so it fought. Or if you prefer the states rights formulation, white southernors believed they had the God-given right to determine whether blacks would be free or slaves, and they didn't want any yankees telling them otherwise.
I agree with you but, unfortunately, your counterfactual is totally implausible thus it is hard to take it seriously. If I play counterfactuals, I prefer ones that *could* have happened. The one your offer was pure fantasy in 1861.
There are more interesting (and more plausible) counterfactuals regarding slavery. For example, what if the Constitution (and its Fugitive slave clause) had never been ratified. What if Jefferson had insisted that the slavery be banned from the Louisiana Purchase (as he did with the Northwest Ordinance)? What if Texas had been been required to abolish slavery once it came in as a state?