This soldier was probably like most men that served in the Confederate army --from a rural or farming background, with a modest family income, and not a slave owner, who was defending his country's right to exist as he saw that right. As a soldier in the Army of Northern Virginia, he was simply an instrument of his government's policy, and since you know nothing of his personal background you have no right to judge him or belittle his service to his government. You cannot judge him using today's politically correct ideas in the context of the social and political world that existed 150 years ago.
I don't think that anyone in today's world can morally defend the inhumanity, injustice and cruelty of slavery. Nor can anyone condone the horrors that occur during war. But I would remind you that what the Army of Northern Virginia did on Pennsylvania soil to gather supplies and provisions was absolutely no different than what Gen. Hunter and his Union army did in the Shenandoah Valley or what General W.T. Sherman's army did on their march from Atlanta to Savannah. As a matter of fact, in accordance with General Lee's Order #73, the Army of Northern Virginia was not nearly as destructive as Hunter or Sherman. Before starting his march to the sea, Sherman requisitioned copies of the 1860 census for Georgia to see where the richest path for his armies lay so that they could "live off the land" without having to depend on a long supply line.