The idea of dyeing a rhino’s horn pink is not absurd. It’s everything else about the 21st-century rhino-human interface that’s ridiculous. The pink-horn notion is a serious proposal and it’s as sane as the whole thing gets. There are plenty of other wacky notions out there. One is to drill a hole in a rhino’s horn and fill it with poison; the idea of the dye is to mark the horn as a poisoned one.