Among the questions I've been asking in response to this form of argument is: how does the very same art magically become not held in trust when a museum decides to sell it to buy more art?
Newcurator makes a different, but related, point. Noting that the piece argues that the National Academy should have sold its Fifth Avenue building rather than two paintings, he says: "So, because there are bigger museums nearby, the National Academy Gallery should sell the building that was donated to them by the Huntington family in 1939?"
Or, put another way: why isn't the building "held in trust" for the public too?