The S&P 500 may not be a fund itself, but Standard & Poor's is a business whose ability to sell services is correlated with the continued relevance of the S&P 500. It absolutely does balance interests - namely, its own - beyond simply being an academic vehicle for communication of a stable thesis.

It seems entirely reasonable to say: "if we make a certain decision, we correlate both our reputation and a nontrivial portion of the U.S. economy with the whims of one of the most volatile personalities in industry, and we should likely pay attention to this trial balloon that shows such anticipatory fear of the decision that we might lose our reputation as an index altogether."