Badar is the Australian spokesperson for Hizb ut-Tahrir, an Islamic political movement whose goal it is to establish a worldwide caliphate, in other words, to bring the world under the rule of a global Muslim theocracy, ruled by shariah law, including Australia. Were the festival organizers aware of this when they invited him, or that this movement is banned in some countries?
I pray that Islamists, or indeed theocrats of any persuasion never achieve their aims. Any theocracy is neither desirable nor feasible. The Islamic caliphate is definitely a dangerous idea. If there is one positive thing to come out of this controversy, it is that more people will become aware of it and other Islamist movements, and make an effort to be properly informed about them. Be alert but not alarmed.