To be fair PE, the CG did not state "the exact opposite." The CG just stated that the numbers are meaningless except in new construction. His statement is debatable.
He is not alone in his contempt of the cost approach:
"A third method of appraisal is somewhat tentatively and timidly put forward by the claimant, namely, the reproduction method. Here an expert is called upon to give his version of the sound value of the building by estimating what it would cost to reproduce it, and then deducting a fair amount for depreciation. This "method" is perhaps the most excellent example conceivable to demonstrate that none of such abstractions ought to have a place in the search for market value, generally speaking. Ignoring the fact that on the figures an absurd result is reached, it is apparent that the reproduction method is in itself absurd in the ordinary case, because even in ordinary times it is ridiculous to suppose that anyone would think of reproducing this or any like property, and that same thing would be true in the vast majority of cases, I should think."
United States v. 49,375 square feet of land in Borough of Manhattan, 92 E. Supp. 384, 387-388 (S.D.N.Y 1950), affirmed per curiam sub. nom. United States v. Tishman Realty & Const.