"Have you been... reading too many novels?"
After listening to Wen Hong describe recent events and her analysis that 'Yin Yinyin might be Qing Lan', Yin Minghong's first reaction was outright disbelief—he had interacted with 'Yin Yinyin' and couldn't imagine 'Yin Yinyin' was actually a woman.
It's not that he discriminates against women, nor that he believes 'Yin Yinyin' couldn't be a woman, or that only men could lead White Night in circles... but even excluding voice interference, Yin Minghong could instinctively judge whether 'Yin Yinyin' was male or female.
'Yin Yinyin' gave him a feeling very similar to that of the Assassin Le Yu, so Yin Minghong did not initially doubt 'Yin Yinyin'—Le Yu was a white-haired assassin, thus 'Yin Yinyin' must also be a white-haired assassin.