>I care more about children (not to mention the other people they will harm) than about the feelings of an adult with BPD.

This isn't about anyone's "feelings," this is about not affording people fewer rights because they carry a specific medical diagnosis.

>My hope is that such an adult would do the responsible thing and choose not to have children, and spend that energy on making themselves better (which is a difficult, lifelong and worthy task).

Again, you're oversimplifying, not everyone with any mental illness is the same. With proper treatment and patient understanding, people with BPD can absolutely be stable and well-adjusted enough to form a family. I'm not sure why you think they can't? Would you say the same of depressed people, because of the likelihood that they might off themselves while the child is at a crucial stage of development? I'm not making this personal as a way of scolding you morally, but I personally suffer from unipolar depression, ADHD, and gender dysphoria, all of which could conceivably make me a worse parent if you allow them to define who I am as a person.

These are absolutely difficult questions, and their ramifications require a depth of consideration you don't seem willing to give them.

>No, it's not an easy policy to enforce, or to enforce fairly.

This is sort of the whole problem though, and once you take out this bit, it becomes tautologous very fast: would I eliminate
any and all factors that harm children and their development in theory if I could? Absolutely, but that's not what we're discussing here. The moral content of these proposals can't exist outside the legal framework that would make them possible, and so other things must be taken into account.

>The diagnosis is inevitably subjective. This is a fundamental difficulty in dealing with all forms of psychological abuse.

Of course, and as always the focus needs to be on the harm it's causing the kid and not on the parent's theoretical potential for successful child-rearing based on inherent qualities of their character or mental illness. I'm sorry to draw this comparison, but that's how the religious right justifies banning gay adoption when kids grow up just fine with gay parents. You're pathologizing borderline personality disorder as defined as being a bad person, and it doesn't work like that. There are ghastly parents who are awful to their children but suffer no discernible mental illness themselves, and there are parents who suffer from mental illness but raise great children in spite of their own suffering and while coping with it. It's just not that simple.

>If only there was an equivalent way for kids to come forward with bruises and broken bones or saying "Mommy touched me in my naughty place"!

I'm a little uncomfortable that you're so focused on women here, because it's not just women who suffer from BPD, and there's a lot of research that suggests the stigma around it and around mental health care is what prevents men from seeking treatment, because mental illness is a sign of weakness and patriarchal society demands that men be strong, violent, and largely unemotional. See for example Wikipedia's gender section on BPD, which is itself a great cross section on why mental illness is seen as feminine in Western culture and how there are tons of men who meet the criteria for ASPD or BPD but we ignore it because the qualities of those disorders are often seen as positive when they're exhibited by men: https://en.wikipedia.org/wiki/Borderline_personality_disorde...

Particularly I don't understand why you're tying this to sexual abuse, because it's not really related to BPD and making it seem as such is enormously offensive to the overwhelming majority of people with mental illness who are not sexual abusers. It also denies people who do commit sexual assault and abuse responsibility for their actions under the guise of pathologizing them, when really the solution to sexual assault is to teach people why sexual abuse is bad (genuinely) and work on fighting rape culture. Being a rapist is not a mental illness.

>But this is precisely why BPD adults should not to have kids, because the harm is extremely difficult to detect. Prevention is better than cure.

Yes, but you seem to think we could prevent stuff like this from happening by screening for mental illness in parents, which I'm not convinced would do less harm than good even if you had a perfect screen. If we can prevent it, we should, but that does not extend to violating civil liberties and basic human rights.

>I'm not an expert, but I strongly suspect that the harm of psychological abuse is 10-100x the harm of physical or sexual abuse, both to the child and to society.

I'm not sure how you would quantify that, but I disagree. I think it seems that way because mental illness and the other results of psychological abuse are vastly misunderstood by most people and psychiatric treatment is both politically controversial and culturally stigmatized.

>But too often people say "it's none of my business" even when they would have said something if there was a broken bone.

Definitely, and this is an enormous problem both with how we treat mental illness in our society and how we think about it. But I think the attitudes that would define people by their illness as you seem to want and slot them into moral categories as such are part and parcel with what is backwards about that attitude: being diagnosed with a mental illness is a guarantee of having that illness and little else with regards to behavior (sometimes even less, as you mentioned that diagnoses are subjective even though well-trained psychiatrists absolutely can often recognize these things without too much trouble.)

The moment you go blaming social problems on mentally ill individuals is where you jump the gap from raising awareness of mental illness to stigmatizing people and putting them in a box based on a diagnosis. The former is an admirable and extremely important goal, and the latter is an unenlightened continuation of present regressive attitudes towards people with mental illnesses.