Right? If you're asked not to speak at a conference, why would you go on to consistently prove it was the right decision to remove you?
As another person mentioned, DerbyCon got tired of dealing with it (https://www.derbycon.com/blog/derbycon-9-0-every-beginning-h...). And then had to respond to a bullshit storm related to their integrity a month later (https://www.derbycon.com/blog/derbycon-clarifications-inclus...).