To anyone who’s followed the case of Emma Sulkowicz, Columbia University’s “Mattress Girl,” the fact that her symbolic protest doubled as a credit-earning work of performance art seems a fitting commentary on the whole situation. Sulkowicz, who graduated Sunday, spent her senior year hauling a 50-pound mattress around campus to protest the Columbia administration’s failure to expel her alleged rapist. It would be difficult to overstate the adulation showered upon her: She won the National Organization for Women’s Susan B. Anthony Award and the Feminist Majority Foundation’s Ms. Wonder Award; she was the subject of a glowing New York Magazine...