Another silly canard. The slavers had no - zero, zip, nada desire to be “left alone”. They demanded that the other states hew the line with whatever bullsnot that the slavers came up with and routinely threatened to “take their ball and go home” whenever they didn’t get their way.
Once they declared their pretended secession they started stealing everything that wasn’t nailed down - and much that was. They forced the governments of Arizona, New Mexico, and California into puppet states. They conducted guerrilla warfare in all of the border states. He had no desire to be “left alone”.
First , taking ones ball and going home is by definition wanting to be left alone. Only a bully then chases the kid home and forces them to play.
The border states fought amongst themselves with plenty of bad players on both sides. Lincoln made this worse by using force to pressure states like Missouri to fight.