At a time of far too much equivocation — by corporations, governments and nonprofits — about the rampant violation of human rights in China, a statement from Steve Simon, chairman and CEO of the Women’s Tennis Association (WTA), rings out like the proverbial fire bell in the night. At issue is the suspicious disappearance of Chinese professional tennis player Peng Shuai, a 35-year-old woman formerly ranked No. 1 in doubles worldwide. Ms. Peng vanished after Nov. 2, when she posted an accusation of being sexually assaulted by a former member of the Chinese Communist Party Politburo, Zhang Gaoli. Her only...