For a more detailed response, see Declaration Of Independence--With Study Guide.
The writer is endeavoring to tear down Jefferson, and others of the Founding Fathers, because he like Jefferson, Madison and many of the others, is critical of the labor system at that time in America, and thoughout much of history world-wide. Recognizing flaws in a system, does not translate into determining how to correct those flaws.
The current obsession with slavery in America reflects a deliberate effort to disparage our heritage. That it is seldom put in context; virtually never put in the perspective of being similar to what existed and was accepted in Biblical times, and from Biblical times onward; never, discussed in the context of how much more humanely the system was administered in America, as compared to other places in the world at the same time or over the millennia, etc., all tell us that it is not genuine analysis, but a deliberate effort to disparage the greatest generation of Americans.
Good post.