Phillip Kennicott, going back to January 26, WaPo.  574 comments at this writing.  Apologies if someone already posted about this earlier and I missed it...

The Guggenheim has said no to the president of the United States, which is a powerful gesture in itself. But it has also presumed to offer him something “more” valuable according to the value system it imputes to him: a tawdry love of gleaming gold fixtures, common to vulgar despots all the way back to Midas himself. The subtext here is: We assume you only want the van Gogh painting as a status symbol, which we refuse to endorse; but we will give you what you really crave, which is crass gold. If he accepts the golden toilet, he confirms their view of him. If Trump declines the golden toilet, by implication he would seem to believe that there are things (such as van Gogh paintings) that transcend money and commerce. And thus, he may undermine his own worldview, in which all things have their price and anything can be exchanged for something else if the money is right.