"“The goal,” she said, referring to feminism throughout history, “was always to say that biology was not destiny because that was precisely the argument that people used to keep women in private spaces: that women with their ‘smaller brains’ were ‘prone to fainting’ and are not fit to be in public spaces, such as politics and the workplace.”"
She is talking about gender here, not biology. For good or bad, biology is actually destiny for women. Women are excluded from politics and workplaces because they have babies, (without access to contraception many, many babies) and they are excluded from some manual jobs because they are comparatively smaller and weaker than men.
Luckily in a country like the UK in 2018 we do have access to contraception and fewer and fewer jobs rely on physical strength, but there is no reason to assume we can take this for granted. Even with a high degree of control over fertility, women still bear children and many jobs don't accommodate that.
Except Emejulu is not baffled at all. For her, many feminists who oppose trans rights also ignore the rights of black, Asian, and other ethnic minority women. These exclusions are related, she said. “This has always been the dark heart of white, feminist politics: a jealous guarding of the boundaries of who gets to be a woman.”
Can never understand the supposedly 'woke' argument that excluding a black women is exactly the same as excluding a white man from the concept of being a woman.