There are some significant barriers to organizing the event in a safe way. The venue which has always housed the event is quite simply way too small for the number of attendees, and it's scheduled during the peak of Europe's flu season.
The organizers could have instituted a much stronger health policy: mandating masks, providing rapid tests, and ensuring proper ventilation in their developer rooms, but the event is largely run by volunteers who likely do not have the training to deal with those who might object to any kind of enforcement.
It's surely a really difficult situation to be in.