That's sweet.
It's really not the point though. If single sex does not mean single sex in law, in all situations, how do you plan to use that law to keep those men out of changing facilities and prisons and hospital wards and HCP roles and refuges if they're sad about those too and other women say they don't mind?
You've just recreated a wobbly permeable line that gives power to men to destroy women's boundaries, spaces and rights in law, and it's been destruction tested for the past ten years that men will. Vigorously. Without the faintest conscience.
The only way to protect women in those vulnerable spaces is for single sex to mean single sex in ALL contexts, ALWAYS, rigidly. And sentiment has to go. That some women don't mind THIS bit is irrelevant. That the man is sad and he's a nice man is irrelevant. The minute you start aww blessing you've returned Sandie Peggie to having to take her clothes off with a spectating bloke and all the rest of it - including the women raped and assaulted. You can't have it both ways.
The judgment's very simple. If it's been made single sex, it was single sex for a reason. Therefore none of the opposite sex, at all, regardless of situation or certificates or feelings or anything else.
The WI does not HAVE to be single sex. It has the choice not to be. It's entirely welcome to announce it's welcoming men and changing it's name and brief, that's entirely it's decision. What it can no longer do is say it's single sex and seek to admit some men. And that's not because anybody fancies being mean to men for a bit of a giggle. Everybody needs to tear their eyes off these men for a minute and see the much bigger picture and all the women behind them.