Don’t even grant the premise. The State’s Rights argument is entirely bullshit. The secessionists controlled the federal government and slavery was federal law. It was abolitionists in Wisconsin and Vermont that were freeing escaped slaves, and new territories wanted to vote to determine whether slavery would be law. The South opposed their right to do so. Lincoln had not threatened to free the slaves before the war, he just wasn’t willing to enforce the federal Escaped Slaves act. That was all it took for the southern states to try to leave America.

But you don’t have to take my word for it.

[A]n increasing hostility on the part of the non-slaveholding States to the institution of slavery, has led to a disregard of their obligations, and the laws of the General Government have ceased to effect the objects of the Constitution. The States of Maine, New Hampshire, Vermont, Massachusetts, Connecticut, Rhode Island, New York, Pennsylvania, Illinois, Indiana, Michigan, Wisconsin and Iowa, have enacted laws which either nullify the Acts of Congress or render useless any attempt to execute them. In many of these States the fugitive is discharged from service or labor claimed, and in none of them has the State Government complied with the stipulation made in the Constitution. . . .

The only time secessionists invoked a state’s right to do anything was to secede.

https://youtu.be/-ZB2ftCl2Vk?si=H6oyy-o3n_J4RhoL