Why don't you? It's historical fact that black slaves existed in Arabia, and later, the Ottoman Empire. It's a fact that many citizens in the Middle-East can trace their ancestry back to black slaves who were taken from Africa. It's a fact that Westerners purchased black slaves from Arab slave traders. Jesus Christ, you really are desparate, clutching at any thread to try and revise history.
I've already answered this in a discussion with Bells. Slaves were not unpaid labour in the Muslim world, they were viziers, ministers, generals, they were elite army corps and they could buy their own freedom. The children of slaves were not slaves. Comparing western slavery to slavery by the Arabs and Ottomans is like comparing sweat shops to a corporate job.