It's been a year and a half since my social world shut down, and I miss my queer- and trans-only spaces dearly. But in that time I've been able to reflect on the types of crowds I do and don't thrive in, and I've come to a realization: I'm over "marginalized genders only", a.k.a. "no cis men", attendance policies.
"No cis men" is almost always shorthand for "no problematic behaviors that cis men are known for, given their unexamined privileges under patriarchy and White supremacy". This is, technically speaking, a "fuckin' mouthful" which we should be able to shorten, but falling back to this particular shorthand has some "fuckin' problems".
First, "no cis men" does not make a "safe space" because it doesn't spell out the bad behaviors which we don't want cis men to bring, nor does it acknowledge that cis women and trans people of all stripes can perpetrate them too.
Second, "no cis men" doesn't make sense from a solidarity standpoint either. We know that marginalized genders don't share the same oppressions, so grouping them together is not to let them commiserate on shared experiences, but to work toward diverse goals with their shared strength. And when we want an umbrella group for solidarity, we don't stop at just gender minorities: we bring in sexual minorities and the whole LGBTQ+ assembly, and we highlight intersections between queerness and race. Again, "trans only", "queer only", "women only", etc. spaces should exist, but when solidarity is concerned, the exclusionary groups (including "marginalized genders only") fail from the start.
Third, "no cis men" suggests that their unwanted behavior is inherent and unique to their nature, which is just sex essentialism in progressive-sounding language, and transsexuals will see right through it, even if they don't realize it. Trans men will wonder why they're not excluded for their "male energy", and trans women will second-guess their every action for fear of coming across as "too male".
Fourth, for the sake of attracting an audience it always pays to define who you want as your group's membership, rather than who you don't. If you want a women-only space, say that. If you want a trans-only space, say that. Tell people they're wanted, rather than "we'll settle for you."
Lastly, and this is a personal detail, I'm just through with hating men, okay? Both sincerely and ironically. Yeah, yeah, "men are trash". You know what? It's too easy for pre-transition trans-fem types to think they hate men, when who they're really trying to hate is themselves, but they keep missing. Distancing myself from maleness slowly allowed myself to actually appreciate it for what it is. Maleness and masculinity are Good, Actually, whether it's embraced by trans-masc people or folks born with their own cocks.
There is no original sin, behavior is learned, and behavior can be unlearned. Just tell people what constitutes acceptable behavior and enforce it.