When it comes to institutions cancelling speeches due to threats of violence, hate speech, etc., we shouldn't conflate the refusal to provide a platform with restriction of free speech. There are other outlets. You might as well complain that a newspaper not printing your controversial letter is an attack on your freedom of speech. It isn't. You can always go down the pub and sound off, or get on your soapbox, if you can find an audience. The vast majority of people could never get to speak at a university event in a month of Sundays. That is not a restriction on their freedom of speech. It's a reflection of the fact that they are not prominent people with particular views. You don't have MORE freedom of speech just because you're a celeb. You just have more outlets available to you, that's all.