I've just spoken to the woman who is organising it. It is going ahead.
I'm going to check in with her later to get the definite venue. And I'll post that here. If there is trouble, it will be moved to a private venue.
She has been harassed, threatened, doxxed. She works for an independent retail outlet and transactivists are determined to get her fired. They are leaving dozens of reviews on the site. Her bosses are now seriously considering their position, as it is effecting their business.
From what I can tell, she genuinely wants a civil discussion. And has been shocked, but hardened, by the backlash.