Slaves slaving for their masters in the Confederate Army were not soldiers. Until March 1865, it was against Confderate law for black people -- slave or "free" -- to bear arms. While a handful may have picked up a gun here or there, the whole notion of black Confederate soldiers is a hoax -- and an insult to the memory of the 210,000 black patriots who served in the U.S. Army and U.S. Navy during the Civil War.
What's your point, exactly? You might as well have said that unless a soldier serves in the infantry he's not "really" a soldier. There are plenty who serve without weapons.
That is a little over the top, don't you think?
This soldier may not have carried a gun but so what? He served the Confederacy. He deserved this honor.
He enlisted, held the rank of Private and was discharged. Doesn't sound like a slave to me.