This article is ultimately soporific.
The argument tries to make moral relativism and moral diversity or moral pluralism synonymous but in the process hopelessly garbles the meaning of moral relativism. The argument also doesn't understand itself as it sits on the brink of an insight it fails to think through: it says Deadwood at its core measures the distance between conventional pieties and political moral self certainty (see my last sentence) as modes of a moral absolutism and the absolute inversion of those pieties and self certainties in its representations of evil and depravity as the way things are.
What the true application of the insight should be-and it's alluded to but not finally made out in the article--is the distance between the clinging to the illusions of a beneficent God and sheer self righteousness on the one hand and on the other unassailable evil and depravity as the conditions of existence, under which conditions man must make himself morally whole as best he can. That effort at wholesness can only be dimly realized and occurs in occasional flashes of secular revelation and kindness.
These are evident in Swearengen murdering the ever-suffering reverend to put him out of his misery while at the same time Cochran berates in Job like intensity a God that would allow the reverend so to suffer and that would allow the wretched suffering and human decimation the doctor witnesses in the civil war. It is an essential thematic paradox that Swearengen's act of kindness must come from murder and from his utter cynicism over, and utter disregard for, the value of any particular human life at odds with his own self interested ends.
Finally, the article, in some unintended irony, is itself pious in its jejune argument that at its essence in Deadwood Milch pitches human interconnectedness, the collapsing of self and other, as the route out of the the evil and depravity seeming to mark existence. For the truth of Deadwood is that there is no such way out--these depravities are as indelible on us as the mark of Cain; there is no possibility of the collapsing of self and other. Amelioration, such as it will come, resides only in a tamping down derived from a kind of civic evolution, manifest in law and order, and in the occasional synthesis of interest and goodness in some of the civically powerful--essentially Swearengen--guiding community life and existence.
In this, Deadwood posits the fundamental difference between the evil rooted in, and modified by, pragmatic interest of Swearengen, who can see that what lies in his interest will spring from Deadwood's own civic betterment and the sheer evil for its own sake of Tolliver. For Tolliver can see no such connection and will facilitate the true "cocksuckers"--Hearst and Wolcott--who will themselves try to victimize and corrupt the camp to gain their ends, ends which ultimately comprise detached power and wealth for their own sakes as modes of evil for its own sake.
(Part of the article's deluded piety shows in the stretch of it that sees Deadwood as a critique, in part, of the moral absolutism of George W. Bush.)