Bachman is correct to note there were founders who worked to abolish slavery. The article is very incorrect to say say Adams was not a founder. That's like saying Lance Armstrong is not a cyclist.
Aside from Adams speaking out against slavery, Ben Franklin turned to abolition of slavery with great vigour after the revolution. He was president of the Society for Promoting the Abolition of Slavery and the Relief of Negroes Unlawfully Held in Bondage.
First Cheif Justice John Jay was founder of the New York Society for the Manumission of Slaves in 1785.
Wadhington, Jeffferson, Madison were also against slavery. Contemporary people often fail to realise turning slaves free could have been the worst thing for many since they had no way of supporting themselves.
"Nothing is more certainly written in the book of fate than that these people are to be free."
-- Thomas Jefferson, Autobiography, 1821
"[The Convention] thought it wrong to admit in the Constitution the idea that there could be property in men."
-- James Madison, Records of the Convention, August 25, 1787
"American citizens are instrumental in carrying on a traffic in enslaved Africans, equally in violation of the laws of humanity and in defiance of those of their own country. The same just and benevolent motives which produced interdiction in force against this criminal conduct will doubtless be felt by Congress in devising further means of suppressing the evil. "
-- James Madison State of the Union,1810
"There is not a man living who wishes more sincerely than I do, to see a plan adopted for the abolition of it."
-- George Washington, letter to Robert Morris, April 12, 1786
Now contemporary people say that some of these people owned slaves so they should have set them free. That was easier said than done since many slaves had no eduction or means of support (there was no welfare etc). Washington inherited over 100 slaves and didn't buy them. He kept slave families together and accounted for them in his will.
It was Washngton's desire that slavery end but he understood there were states in the new country that would not tolerate any movement to do so.
In a private letter in 1786 he stated, it is "among my first wishes to see some plan adopted, by the legislature by which slavery in this Country may be abolished by slow, sure, and imperceptible degrees." He understood the commitment was to a cautious and gradual process and never allowed his anti-slavery position to be known publicly. He feared that such action would deeply divide the new nation
Aside from freedom, slaves who were children were to receive occupational training and to learn to read and write - elderly slaves were to receive financial support. Washington insisted that "this clause respecting Slaves, and every part thereof be religiously fulfilled ... without evasion, neglect, or delay."
Franklin understood slaves needed training
Franklin wrote "Address to the Public," in which he addressed the education of former slaves. The plan was to "instruct, to advise, to qualify those who have been restored to freedom, for the exercise and enjoyment of civil liberty; to promote in them habits of industry, to furnish them with employment suited to their age, sex, talents, and other circumstances. . . which we conceive will essentially promote the public good, and the happiness of these hitherto much neglected fellow-creatures."
Vermont ended slavery in 1777. PA in 1780 and NH, MA and CT in 1783 and 1784 . RI and NJ in 1799 and 1804. The actual end of slavery in these states was not long behind the official end. Congress did act to ban importation of slaves in 1808. There was quite a lot of action to curtail slavery on the part of founders. Slavery was brought to North America was founded. The founding of America is what would end it.