I might not be remembering it correctly, but it looks like MH's statement / position is being misunderstood by some.
She said there is a big focus in mainstream feminism that women in general should be thrilled about having careers as if this is the most important thing in life. However, from her point of view, many women prefer to focus on family and actually would like to have more children if possible. Career is not the most important thing above all else. It's not about women being pressured into having children for the greater good - they actually want to be able to have more children. And it's not about being chained to the domestic sphere either. Most women want some combination of work and family life balance, but with maybe more focus on family rather than work.
However, for various reasons this is not possible. There is societal pressure thanks to a certain type of feminist thought that women should be maximising their educational attainment and then career achievements, which means less time and opportunity for having more children because of the general fertility window (which is a real, biological constraint of our sexed bodies that women cannot escape, unless you move towards surrogacy etc).
The capitalist structure of the modern economy is also geared towards pushing women to focus on career rather than family because this expands the labour market, increases economic productivity etc. So rather than "women being made to have children for the greater good" it's the other way around - women being made to have less children for the greater good i.e. for capitalism and a certain type of feminism. If you don't buy into this concept then you can feel like you're 'letting your side down' which is an indication there's a subtle but pervasive pressure on women to focus on career at the expense of motherhood.
Wherever this combo of capitalism and career focused feminism has taken hold, the size of the family has shrunk and women, on average, end up having fewer children as most of their productive years is spent on career rather than family. Motherhood is viewed as something that gets in the way of women's economically productive lives and an inconvenience to overcome as quickly as possible, rather than an important and meaningful part of many women's lives and something they prefer to prioritise over career achievements.
According to career oriented feminism, this is all a good thing, and maybe it is, but everything has downsides and unintended consequences. That was MH's point as I understood it - what are the downsides and unintended consequences of a feminism that ignores motherhood? Is there a way to honestly talk about that?
With women having fewer children (than they would like) this results in smaller families and a gradual decline in population. A declining (and aging) population then needs to resort to more and more immigration to prop up the economic and social system. Greater immigration leads to rapid changes in demographics which can affect community cohesion. It's human nature to feel worried and anxious about local culture and sense of identity and belonging being eroded when there's rapid changes in the population due to increased immigration. This can lead to increasing hostility and resentment towards people who are 'not like you'.
This disruption can also affect societal view of women with a growing political movement that seeks to curtail women's reproductive rights. If such political movements are successful, and women's reproductive rights are undermined, then women will end up having more children whether they want to or not, which also means their educational attainment will decline in the long-term because women will start having children at much younger ages again which will impact on their ability to pursue further education.
So career oriented feminism might end up causing the very problems it set out to resolve in the first place. I think that was the point MH was trying to make and I thought it was an interesting (if dystopian) line of thought that I haven't come across before.