“Jefferson’s universalistic vision of human rights challenged the Anglo-American principle that freedoms flowed from a specific group’s identity (Britons never will be slaves). Jefferson did not believe that Americans were free because they were Americans or Protestant Christians. He could not credibly claim that the values he promoted were truly universal unless he showed that they applied to Muslims as well as to all other men. For Jefferson, deconstructing Orientalist constructs was a precondition for the success of liberty in the United States. . . . ”
Yes, Jefferson had slaves, but the article is talking about how the idea that Europeans should NOT be slaves developed in the context of fascination and also much interaction with things Ottoman, including being enslaved by the Turk, and then how, under the influence of Islam (Jefferson was under the influence of Islam) they started to believe rights were universal. THERE ARE SO MANY TWISTS AND TURNS TO ALL THE LOGIC ABOUT ALL OF THIS THINGS, IT IS FASCINATING AND STRANGE.
Earlier in Europe, the line “Britons never shall be slaves” referred to hopes of not being captured by Muslim seamen and enslaved by the Turk. (The idea was growing that Europeans should not be slaves, and that freedom was based on identity; interestingly Jefferson the slaveholder is the one who worked on the theory of universal and not identity-based rights.)
Axé.
coldhearted scientist وداد 
“Rule, Britannia, rule the waves; Britons never shall be slaves” originally referred to the hope of evading the Ottoman sailors who were so successful at capturing and enslaving people, like Miguel de Cervantes, on the high seas. See Sean Foley, “Muslims and Social Change in the Atlantic Basin.” Journal of World History 20:3 (Sep. 2009): 377-398. U of Hawai’i Press.