The opening night of the London Feminist Film Festival last Friday seemed like a huge success: Myriam Fougère's Lesbiana – A Parallel Revolution, about lesbian separatist communities in North America in the 1980s, was originally going to be screened at one of the smaller screens at the Hackney Picturehouse, but was moved to the biggest one after it sold out, and then sold out again. Unfortunately, the film didn't end up in the centre of the event. Chair Femi Otitoju managed to introduce the panellists – director Fougère, politician and activist Linda Bellos and anti-porn activist and academic Julia Long. But even before the floor was opened for questions, Long raised her hand and asked all the men in the audience to leave.

There was an instant uproar: lots of clapping, but also lots of booing. Many men and women got up and left, visibly disgruntled. Long then elaborated on her point, saying how "politically disastrous" it had been to allow men to attend feminist events and conferences in recent years (although she did not specify what the harm actually was). She made some further controversial claims, such as that heterosexuality can be a death sentence (no, that's conflating it with abuse), or that in the face of "off the scale" sexual violence and misogyny, there's nothing more threatening than women withdrawing from men completely (how very progressive and change-inspiring).

Meanwhile, most questions from the audience, rather than referring to the film, opposed Long's request: "Some men were here to learn, and it's not a simple binary, not all of us are men or women," said one audience member. "You have to know your allies," said another, "changing the dynamic of what is a public screening was not fair. Your invitation was not in my name."

Some voices managed to come through about the actual film: people asked how women managed to fund their communities, which inspired Fougère to share some incredible stories about building houses simply from surrounding trees, or about how some women were split between still working "out in the world" but coming back to the communes as their homes. She made a comment that could have inspired a huge and fascinating discussion: "You did it for a year or two, but you can't be an activist and separatist forever, you move back to your functioning toilet at home." An audience member talked about the history of the Lesbian Line, and another underlined the importance of archiving and oral history. Fougère replied saying she will leave all the material she used for the movie – 35 interviews – in a New York library. And that's what the whole discussion should have been about.

Yes, Lesbiana is a film about 80s lesbian separatism, and the film examines the relief that not having to deal with men at all has brought to the women involved. Like any other perspective, it's worth hearing out. It's also worth debating, but in context. What was said in completely different circumstances 30 years ago cannot by default apply to the here and now, especially if the open film screening wasn't advertised as a women-only event. It's not even about the fact that people paid to attend: it's about outreach, inclusivity, and intersectionality.

I agree with Bellos when she says women-only spaces are important. I agree with her when she says women can't hold men by the hand, that there's work to be done by men to redefine masculinity. I agree that it's not obvious what role feminist men can assume within the movement without derailing it and taking power away from women. However, patriarchy hurts men too – something that does not erase the damage it does to women, but underlines how important it is to reject bankrupt binaries when they are damaging. .

The London Feminist Film Festival has since apologised to anyone who was offended, saying they were "not aware that the panellist would make this comment and, while respecting the politics of the panellist, [do] not condone her comment. All are welcome at all LFFF sessions." In my view, what Long suggested completely derailed the night's debate. Not only was it offensive to assume the authority to change the dynamics of the space, but also deeply unfortunate to take the time and attention away from the artist and her film, and all the people involved. They deserved better.