This is a case of the tail wagging the dog. That is, the author writes as though the legitimacy of free speech in academia is dependent on whether Oxford Union

This is a case of the tail wagging the dog. That is, the author writes as though the legitimacy of free speech in academia is dependent on whether Oxford Union debate can be shown to be legitimate. Rather, let free speech be deemed an axiomatic truth with the propriety of Oxford Union debate a simple corrollary issuing from that.