This is, essentially, the entire argument for women's and LGBT+ rights in a nutshell and even a notorious transphobe like Kathleen Stock can't avoid resorting to it.
What people call "biological realities," firstly, are socially determined, as they frequently include mandatory heterosexuality, gender conformity, and subordination of women and AFAB people for the sake for forced reproduction backed up by state and interpersonal violence.
Queer and intersex people, as well as women who don't want have children, are frequently labeled "unnatural" under this system even though we obviously exist.
And there is no doubt a great deal of biological nuance and complexity underpinning sex, gender, and sexuality, as emphasized by differences in sex development and the various structural differences which have been observed.
The more important point, however, is that whatever biological causes or contributions exist to sex, gender, and sexuality, individual freedom and human happiness are understood by all but the most illiberal, reactionary, and fascist social orders to take precedence over any so-called "biological realities."
We may never know, for example, what causes someone to be gay or trans, but we do know that attempting to suppress them achieves nothing but suffering and misery on a widespread basis.
Likewise, women and AFAB people who choose not to be pregnant are exercising their right to bodily autonomy -- a right which is implicit and understood for cis-het men and only becomes "controversial" when it runs counter to their desires and the prevailing white supremacist patriarchal Christian social order.
Whatever "biological realities" may be claimed about women's bodies and our "natural" and "necessary" roles as mothers, we still have the right to choose for ourselves how we live.
Kathleen Stock is obviously aware of this argument and the deep feminist history underpinning it; she simply refuses to follow her own argument to its logical conclusion when applied to anyone except other white cis women like herself.
In fact, like a lot of TERFs / GCs, she makes allowances for cis queer women while absolutely refusing to show the same level of care and compassion for anyone else.
No doubt because, as a deep-thinking academic philosopher, she thinks trans people are "icky."
There's a reason that arguments based in so-called "biological realities" are extremely suspect, as they have a well-known basis and history in misogyny, racism, and eugenics.
The only people who still use them are fascists, which is indicative of the politics of TERFs / GCs / transphobes.
But as they've started to feel the consequences of allying with fascists, they're compelled to defend themselves with the same arguments as the rest of us.
When, of course, the fascists don't care.
There will be a splintering of TERFs / GCs as these useful idiots for fascism find themselves increasingly under attack by the theocrats they've boosted to hurt trans people.
Much as conservative white women in the US have started slowly feeling alarmed by the religious extremism of the GOP, which they previously assumed, apparently, was all talk.
Of course, the wealthier and more bigoted white women will no doubt stick with the fascists in pursuit of status.