and we have the choice whether we platform them
No we do not, except by the choice of making the events closed and invitation-only, which changes the entire nature of the event.
This is very simple. An event is either open, or it is closed.
A closed event has a thing called an "invitation" where you "invite" known people, and thus have some control over who attends.
An open event does not have invitations. Anyone can participate buy turning up, or buying a ticket.
Open events do not vet who turns up or buys tickets, nor do they have the ability to do so. They can have behaviour checks inside the venue, and can eject people, but there's no pre-vetting.
So, for example, your Jolene whoever-she-is can take a bus, go to a Sam Smith concert, post on Mumsnet, or even attend and speak at a Let Women Speak event. Those are all open.
If you want to prevent her or any other Bad Person from doing any of those things, those things have to stop being open to permit the vetting by a designated Good Person to take place.
She has the choice to invite and vet people, but then they wouldn't be "Let Women Speak" events any more. Just as Speakers' Corner has the choice to not platform people, but if it didn't it wouldn't be Speakers' Corner any more, and women's spaces have the choice to admit men or not, but if they did they wouldn't be women's spaces any more.
All of those are not about individuals, it's about a fundamental mode of operation - open or closed - so in all cases focusing on individuals is disingenuous and avoiding the fundamental question.
PS using an open platform like Mumsnet to decry open platforms seems a tad hypocritical.