If it's a group who rely on the public to fund it, it loses my funding instantly & forever.
Even if they 'change their mind' I'm not putting money or time into a group who might change their mind again.
If it's a group that relies on women volunteers or donations they drop.
You immediately permanently exclude women from faiths or cultures where they cannot share space with the opposite sex.
You also exclude women who are just not comfortable in the prescence of men for their own personal reasons.
Even if it's just being expected to share the toilets with a bloke, the damage is done.
People are scared to complain because TRAs are so vicious & aggressive, so they just drift away quietly & the unisex group dies.
Nobody talks about it much but I've seen it happen to half a dozen groups that were for women/by women, even small ones with only half a dozen people in them.
By letting in this man, you exclude women who sought out a safe space without men in it & take away their voices.
Women sought out that charity because it was women only.
You let in a man, it loses the USP that made them join it & no longer serves it's purpose.
There might be a few handmaidens who keep it going for a while, but it's a death knell long term.