It's so bizarre the way Dr McKinnon seems unable to follow their own arguments through beyond A-B. In their opinion, if that photo of Sharron Davies was presented to people as a transwoman, many people would think she was a man (argument a-b) and that this would show that people are prejudiced against transwomen because they have what transwomen consider to be masculine features.
And yet, she wouldn't be a man (b-c). Those opinions, if really held, would be erroneous, not because of looks or features, but because of biological reality. Whereas, if Dr McKinnon was thought to be a man, this would be correct. It's almost as if Twitter responses and followers represent reality, and how well you pass is how female you are. It is odd getting a glimpse of profound sex dysphoria and its distorting effect. What was that detransitioner account linked to on here somewhere explaining that the more attention paid to the body and the more medical treatment received for sex dysphoria, the worse sex dysphoria tends to get.