It's incoherent because it tries to claim that the question of whether or not such practices are sanctioned in Islam is nebulously complex and not reducable to a simple explanation one way or the other, while at the same time affirming over and over again that slavery has indeed been a part of mainstream Islamic doctrine and law throughout the history of Islam and since the time of Muhammad.
Ali never, at any point in the piece, actually makes a case that slavery is not Islamic, or cites any examples of a meaningful, mainstream tradition within Islam that rejects slavery. The closest she comes is in this vague allusion to "scholars" somewhere:
Others [sic] scholars point out that just because the Quran acknowledges slavery and early Muslims, including the Prophet, practiced it doesn't mean Muslims must always do so; indeed, the fact that slavery is illegal and no longer practiced in nearly all majority-Muslim societies would seem to settle the point. It is one thing for committed religious thinkers to insist that scripture must always and everywhere apply literally, but it is ludicrous for purportedly objective scholars to do so. Anyone making that argument about biblical slavery would be ridiculed.
That link redirects us to a disingenuous article published at CNN last year, which is authored by a single professor who may not even be a Muslim.
That doesn't exactly push my "Everything's OK then" button.
In any case, this is the only reasonable argument that moderate Muslims can make that slavery SHOULDN'T be practised by contemporary Muslims: that it is part of an ancient tradition and not applicable to the modern world.
And yet such an argument will face massive opposition from committed Muslims, due to its insinuation that the Qur'an itself is not an eternal book, as has been generally believed by all generations of orthodox Muslims, but rather one that goes out of date as time rolls on, and that the word of Allah can be susperseded by the whims of man as the political and cultural winds change. It also risks the wrath of devout Muslims the world over in challenging the contention, held to since the beginning of Islam, that Muhammad is the "Perfect Man" (al-insan al-kamil), and that he presents a “beautiful pattern of conduct” for Muslims to follow (33:21), and displays an “exalted standard of character” (68:4). To say that a behaviour that he accepted and endorsed is somehow immoral would place Ali firmly into the camp of "blasphemer" for many Muslims (and we know what they do with blasphemers...)
Simply put, Kecia Ali doesn't really make a case in this article that sexual slavery is un-Islamic, or even any coherent case that it should be reformed, even as she sets the entire piece up as doing exactly that. She also makes a needless dig at America right at the end of the piece which essentially blames the US for causing Islamic sex slavery.
It's just another example of a dishonest Muslim apologist using a willing mainstream media to lull concerned Westerners back to sleep.
One has to wonder just why Kecia Ali might want to do that.