That's because the Southerners "crime" was not slavery, but daring to defy the corrupt financial cartel running Washington DC.
The criminals take a dim view regarding challenges to their power.
They dress it up as "morality", but the reality was revenge and punishment for those who dared to defy them.
“granted no compensation to their enslavers”
American slaveholders got nothing.
European owners of American slaves were paid I believe.