Did you also know that when Britain tried to put some taxes and regulation on the New England rum industry, the New England states howled that it would ruin their economy. (Rum was used to trade for slaves in Africa) Did you also know that in the Declaration, one of the reasons the colonies gave for breaking with great Britain was that the King had encouraged domestic insurrections (slave revolts)? At that time there were slaves in EVERY colony. Did you also know that Britain offered freedom to all the slaves that joined them in their fight against the colonists?
By the very words of the Declaration of Independence, any change in government for the purpose of perpetuating and extending that ultimate denial of its basic principle, that "all men are created equal," chattel slavery, is not and cannot be legitimate. Any powers such a government might use could by definition not be "just powers."
If you take the words of the declaration to include slaves, then why didn't everyone free their slaves after it was issued? Why did the slave trade continued legally for twenty years after the constitution and illegally for many years after? The new England states fought Britain and it seems that one of their reasons was the protection of their slave trade and rum industry. Does that mean that their fight for government of the people, by the people, and for the people was not legitimate? And who are you to decide what just powers are? The importation of slaves and the slave trade continued for a while after the start of the union. Does that mean our government under Washington, Jefferson, Adams and etc. was not exercising just powers? It was not legitimate?
The Founders were not talking about slaves when they wrote the declaration. Trying to construe such is ridiculous. They considered slavery and the slave trade a legitimate practice and considered Britain's attempt to get the slaves to revolt against them to be despicable.
The point is, a people can separate themselves from an abusive government whether or not they have slaves. The founders didn't think having slaves was a problem when they declared themselves free from Britain. Your argument that having slaves disqualifies one from forming a new legitimate government is ridiculous.
AFAIK, not one of the Founders publicly stated that slavery was a positive good, all viewing it as a great evil, but one that couldn’t be eliminated at the moment without great risk to society and the Union. This is certainly true, by their own words, for Washington, Jefferson, Madison and others who owned slaves themselves.
In hindsight this refusal to boldly face the contradiction between their principle of equality and the practice of slavery was by far their greatest mistake. It would have been much easier to put in place a gradual system of emancipation in the late 18th or early 19th centuries, before the cotton gin made the institution wildly profitable and the South built its economy and society on it.
I hope you can comprehend the difference between recognizing that immediate full implementation of the principles of the Declaration is impractical and proclamation that those principles are obsolete and untrue. See the Cornerstone Speech and numerous other southern proclamations that the Founders had been mistaken. All men are NOT created equal. And to prove it we will spread slavery far and wide both in time and in space.
The root principle of the Declaration is that “all men are created equal.” By its very wording all the other principles grow out of this one. If you reject the foundation, as the CSA did, you are left with no solid base.
Either all men are equal or some are more equal than others. Once you start down the second road, on what basis do you draw the line on who is and is not equal?
In the words of a great man, some years before the War, “Our progress in degeneracy appears to me to be pretty rapid. As a nation we began by declaring that ‘all men are created equal.’ When the Know-Nothings get control, it will read ‘all men are created equal, except Negroes and foreigners and Catholics.’ When it comes to this, I shall prefer emigrating to some country where they make no pretense of loving liberty — to Russia, for instance, where despotism can be taken pure, and without the base alloy hypocrisy.”
Luckily the Know-Nothings never got control, and their spiritual brethren of the CSA were defeated.