Perhaps the author regards a significant number of men as a lost cause.
I would agree with their findings. I dated from 17 to 43 and had four long term relationships. I never hid my desire for a child. but none of the men wanted children. They wanted lifestyle things, BMW's and skiing holidays. No ties or inconveniences. Even my eventual fiance changed his mind shortly before the wedding and announced he had never really wanted children.
When at 44 I fell pregnant (which was quite a shock), I chose not to terminate. Twenty seven years of being messed around and lied to was enough.
I have a kind considerate, affectionate son. But he doesn't want children. He doesn't see the attraction.(Obviously he may change his mind, he's still young).
Men are how they are, they won't change so if women are to have babies at all, they need to do it on their own.