The Rape of Nanking, and Imperial Japan's actions, not just of Unit 731, in the war are well recorded and cited fact. Talking about it is "nefarious motives"?

The Rape of Nanking, and Imperial Japan's actions, not just of Unit 731, in the war are well recorded and cited fact. Talking about it is "nefarious motives"? What nefarious motives are there to remind of a particularly dark period of Japanese history? Pre-revolutionary China was disproportionately a victim of Japan's actions in the 1930s and 1940s. That should be remembered, not taken as cause to make ridiculous claims of psychological manipulation.