I completely agree that the ridiculous amount of hate speech on minority or social justice subs in unconscionable. I give you my full support and many hugs. Also many slaps to the asshole racists.
But we were discussing this in another sub, and it's not clear that having a semi-private sub would do more harm than good wrt to said trolls. Unless the vetting is extremely time consuming, it's very possible for racists to jump through hoops and then spread hate speech. We see this currently, with IP bans or automods not working perfectly - there's people willing to code, and wait a few days, just to get a few lines of vile speech in.
At the same time, I feel like the vetting process would discourage legitimate participation, and tend to create very unidimensional subs. It would prevent the use of legitimate throwaways by people in crisis. With self-selection, you end up with a community that's actually a sub-community of the intended community, all with the same opinions and political beliefs. One of the things I enjoy about this sub and a few POC/social justice ones is that I get to read things from people with a wide variety of opinions, and I feel like that wouldn't really happen in more closed subs.
There's a fundamental tradeoff between an open and inclusive forum and protecting yourself from hateful people. Part of why reddit, including the POC subs, are meaningful places that attract a wide range of people, is because they are open forums and that the users are more or less anonymous. The womens' and POC forums choose to be on reddit, and on open subreddits, and not other less popular forums (or their own forum), because of the popularity of reddit allows them growth and visibility. A large membership and visibility are important goals for social justice causes.
Obviously this is my opinion - but it is one that quite a few people share - I'd rather see a wide range of topics and opinions, from a wide range of people, and run into an occasional hate message, than to be in a very limited and controlled environment that's troll free. Which is why I think having an open sub with a sister private/controlled sub might be a better approach. The private sister sub can be a place to seek support in a safe space, whereas the open sub can sort of be the "public face," where you do outreach and you discuss controversial topics.
While I agree that it's important to get the admins solidarity in preventing hate speech, rather than getting them to make a new type of sub, it might be more useful to get their cooperation in taking down the many, many hate subs out there. Part of the reason there is such a troll problem on women's and POC subs is because reddit doesn't really make much an effort to discourage the hate subs, sending a clear message that reddit is a place where white supremacists and other haters are welcomed. There's sort of a suggestion that civil rights and white supremacy are equivalent ideas on reddit. (It's kind of like haters come to read TRP and the white supremacist subs, and then stay to troll blackladies or twoX.)
I know the reddit admins like to put forward the idea that hate speech is just talk or an opinion. But the reason it's scary is because it ISN'T just talk - there is a clear intent to do harm, and often that intent becomes reality. Wwhile racism or misogyny or homophobia aren't crimes, acting on them are crimes, and they are also hate crimes. Even planning it, which happens all the effing time, is a crime. So it's doable to put forward the idea that reddit admins want to keep reddit from a place where people are planning and doing criminal activities.
EDIT: You are doing a lot with bots and stuff, and I am eternally grateful to whoever set those up. But perhaps they can be improved by looking at the enemy - there are strategies that various misogynistic or hate subs use to keep their subs full of hate. TRP and it's sister subs come to mind. (I won't lie, I'm an asshole and tried to troll TRP with non-misogyny and ran into all sorts of roadblocks.)