If you are to suppose that the Confederate States of America were a legitimate, sovereign government of the Southern states, the term "War of Northern Aggression" makes more sense. They did not threaten to secede from the United States, they
did secede from it. The United States taking action to take back control of the southern states could be viewed as "Northern Aggression."
Granted, it is a little odd considering that the Battle of Fort Sumter was initiated by the Confederates, though you could argue that attempting to resupply United States troops in Confederate territory as an act of aggression from the United States.
In either case, the argument seems to be that Gorbachev being responsible for the death of many lives doesn't discredit the notion that he could be a "genuinely good person" since there examples of people that have been responsible for the death of many that are generally viewed favorably, such as Lincoln.