There is no equation between the "clean hands" of the North and South on this particular issue. Nor is there on the issue of treason, since many of the most prominent leaders of the South (including their God, Robert E. Lee) swore oaths to the United States that they later broke. It's not a simple matter of someone fighting for home, these people specifically swore oaths to the United States. As far as I'm concerned the lot of them are traitors and the South got off easy for its crimes against the Union and Humanity.
What about those thousands of Irish and German immigrants the North essentially impressed right of the boats into the Union army? And those men like Robert E. Lee weren't traitors, they loved and fought for their homes just as much as the men from the North did. The only difference between them is that most in the South say themselves not just as Americans, but ultimately as Virginians, Georgians, Mississippians, etc. A traitor is someone who betrays their home. These men didn't betray their home; they just had a different idea of what their home was. If anyone was a traitor is was Booth, since when he killed Lincoln he not only assassinated the President, he killed the best friend the South had in the North after the war.