Regardless of any previous history between the two individuals, the clear fact is that Anita used the stage and the position of power that comes with it to personally attack an audience member who had not been disruptive to her panel in any way.
She willfully engaged in the exact kind of bullying behavior that she was supposed to condemn the panel on the very next day. Can you not see how astoundingly hypocritical that is?
If you really care at all about the issue of bullying, I would strongly recommend making a complete 180 on this issue. Her critics had every right to attend her panel and listen to her speak.
They did nothing wrong, and if Anita can not control her own behavior well enough to handle simply seeing someone she disagrees with without launching a hateful attack on that person she should not be allowed to speak in public events like this.