Tell me again about the public trust (three paintings by Georgia O'Keeffe edition)

Because they are assuredly not held in the public trust, to be accessible to present and future generations, the three paintings, by Georgia O'Keeffe, are being sold by the Georgia O'Keeffe Museum, to buy … other works by Georgia O'Keeffe?  Fortunately for the Museum, there's no such thing as the public trust or else some people might think this is problematic.