It's vague enough to imply that it's common knowledge, distorted enough to conform to hisao's perspective, and yet still restrained enough to make it seem plausible, at least. And kenji doesn't distort the truth, he isn't out to convince Hisao to join his cause. So it's far more likely to be a fact he picked up on and seized on as evidence for his[s] feminist kill-bot justification [/s] calm, reasonable defense of traditional values.