I don't have a problem with safe spaces. To me, they're like office break rooms. Sometimes you just need a minute to disengage. But, if you're spending your whole day in there, I'm going to question why you show up to work in the first place.
A women-only safe space is sexist, as the implied "safety" of not allowing men implies that men are inherently unsafe. A POC-only safe space is racist, as the implied "safety" of not allowing whites implies that whites are inherently unsafe.
If anyone were to even suggest the opposite implementation, a men-only or whites-only "safe space", then the discriminatory nature is immediately apparent and everyone rallies to shut down the idea before it ever reaches implementation.
Edit: Oops, I've invaded HN's safe space. Disagree with me all you like, but as we learned earlier this week it's not the votes that matter. Tell me why I'm wrong, I'm genuinely interested in hearing your opinion.
> No Person except a natural born Citizen, or a Citizen of the United States, at the time of the Adoption of this Constitution, shall be eligible to the Office of President; neither shall any Person be eligible to that Office who shall not have attained to the Age of thirty five Years, and been fourteen Years a Resident within the United States.
I don't see anything there about genitalia or skin color.
But since it's a "safe space" I think I'll pop in there and relax for a bit. It's time I escape this mediocrity and claim the power of my white male birthright.
It's to give people an opportunity to talk about the impact of a thing without needing to prove that thing exists in the first place. It's like climate scientists not inviting deniers to their conference: they want to focus on the implications of climate change, not debate the existence of climate change itself.
I think there are plenty of reasonable safe spaces that accomplish the thing they were meant to do without resorting to blanket exclusions. The answer to one extreme is usually not the other.
I find that when I personally want a "disengagement break", I get more relaxation in just holing myself up at home vs taking over someone else's area.
As for "taking over someone else's area," to me that's just politics. There are ebbs and flows of power and control. Trump's victory is going to legitimize a lot of criticisms and possibly over-correct, though hopefully we will be in a position to have a reasonable understanding of what a "safe space" should be within the next decade.
Start making "safe spaces" for Trump voters to talk about their candidate without being called ignorant and you'll start to see people's attitudes shift on what the sensible limitation of safe spaces should be.