I think it can be a bit of both. I don't write all women who don't want the child's father to see their kid off as toxic, because there are many reasons why she made that decision; some reasons can absolutely be self-serving and detrimental to the child, and others can possibly be for the child's own good.
If we examine black culture for example, many (not some, many) black men are sexual and/or child abusers. Hell, let's keep it 100: quite a few black kids are birthed from rape. Especially considering that we are a religious race that doesn't believe in abortion.
Pretty much all of us know of some creepy man, either in our family or community, who can't keep his hands to himself. And of course some of these men are fathers who have no business being around children. Yes, this is an extreme example, but it is way too common so I will address it.
On another note, there's also relatability and following the footsteps of other single mothers because that's all you've known for life.
I am not writing off what you've said; I just think it is more complicated than feeling sympathy for a man crying to see his damn kids lol