Case-Shiller Wrongly Accused Of Bias Crime

Realtor Magazine, an organ of the National Association of Realtors (NAR), posted an article that accuses the Case-Shiller index of a bias crime.

Realtor's charge is that SPCS has a downward price reporting bias. They also cite an "unctuous" (editor's memnomic) link to the financial trading community.  The article then uses an OFHEO paper that examines the futures contracts values with the actual index values.  This argument that does not address the bias charge at all (actually has nothing to do with the index itself) and is used as a central argument premise. 

Because the Case-Shiller index diverges from OFHEO's findings, the NAR claims mal-intent and bias.  Yet, as per the article, OFHEO seems to have no horse in this race:

"... In any case, OFHEO researchers admit that they don’t really know the source of divergence between their index and Case-Shiller’s...."

If you are serious about this discussion on housing indices, see Matt Carter's post in Inman News.  Carter rebuts the NAR claims to this high, dry index ground. Point by point, the Realtor argument of bias is taken apart.  It is comprehensive in evidence.

If the Case-Shiller Index were to show upward price movement accelerating faster than NAR or OFHEO indexes, would the Case-Shiller index be lauded and cited as the NAR's index of choice?