Rabbi Lehmann seems to have a rather unusual way of viewing pluralism. It is especially odd since in the 4th paragraph of his "Exodus 18:1-20:23: The Ten Commandments as a Symbol of Pluralism" he notes a specific concern.
"What disturbed me most about the erection of the Ten Commandments sculpture in Alabama over a decade ago was the assumption that those of us who regard the Ten Commandments as fundamental to our religious belief system agree about exactly which commandments were on those stone tablets."
That is a pretty important thing to note. Many don't realize that there is more than one version of the Ten Commandments. Lehmann himself does attempt to harmonize them in this piece but like so many before him he fails miserably. I can only see this as a symbol of pluralism if you take a very narrow view of the term. If he means to recognize the fact that society is divided over religion it works. However, it is clear that that is not his intent. It never occurs to him that some of his own comments point to the Ten Commandments being divisive rather than cohesive among the three faiths (Judaism, Christianity, and Islam) that have any interest in them.
And, of course, he completely ignores the fact that at best all the various other religions of the world would be indifferent to these Commandments. He also never gets into the various theological and philosophical problems posed by the commandments. The majority of these ten are petty, self centered, and hostile to the non-Abrahamic based faiths. If that is pluralism then society is better off without it.