So then the founding fathers were criminals?
This is a very common, yet completely specious, analogy.
The Founding Fathers spent more than a decade begging the British Crown for their fundamental right to representation.
Since the Crown was not willing to acknowledge the rights that its entire claim to rule was based upon, the Founders were absolved of their allegiance.
The states of the Confederacy did not only have full representation in the federal government, the federal Constitution was specifically strcutured to guarantee them overrepresentation.
Free whites of the South were one-fifth of the US population in 1860, yet they elected almost one-third of the Congress, fully one-third of the Senate and had a majority on the Supreme Court.
None of the rights of the Southern people were abridged in any way, let alone abolished.
In the Declaration of Independence they basically acknowledged that their actions would be treated as treasonous by the Crown.
In the eyes of the British? Yes they were.