We cannot say that Rebekah Mercer and her family foundation are dictating museum exhibitions by virtue of her board seat, and the museum, in a statement, has said that she is not and that “its funders do not shape its curatorial decisions.” But that’s not really the issue. As a funder of climate-science disinformation, Ms. Mercer stands in direct contradiction to the museum’s mission “to discover, interpret, and disseminate — through scientific research and education — knowledge about human cultures, the natural world, and the universe.”