IW's point is that trans women and black women are both subsets of women.
IW is wrong. And racist.
Transwoman describes a man who prefers to be referred to as a woman.
The fact that they would also prefer a space between the words is irrelevant. It still means the same thing.
Women are female from the day they are conceived. Black, white, tall, short, whatever, is a description of their noun - woman.
No transwoman needs a descripter of woman because they are not one. If they were, they wouldn't be trans.
Everyone knows this.