Not letting someone publish something because you find it *offensive* is censorship.
Canceling a television show or radio program because it's *offensive* is censorship.
Canceling a speaker from holding a public discourse is *censorship*.
Now, I'm not saying giving certain folks a platform isn't always a great idea (sometimes it's most definitely not).
Broadcasting pernicious, vile, and grotesque ideologies out into the world is always going to be problematic because there are always going to be pernicious, vile, and grotesque individuals which will latch onto those ideas as though they were scripture.
But the very concept of free discourse depends on the fair representation of both sides of an issue / position, whether wrong or right, and then we must allow for the best ideas to win through a thorough examination of their content.
If your idea isn't good enough to beat something terribly awful, then that may be a fault in rhetoric, and you'll have to do better. Otherwise, if your ideas are continually on the losing end, then you should pause to wonder whether or not these ideas are worthy of championing or whether you're just wasting yours and everyone else's time.
The problem with pernicious, vile, and grotesque people, however, is that they often see themselves as heroes, and when their ideas fail they make themselves into martyrs to resurrect such ideas again under another guise.
The discourse is neverending. In a world where freedom of speech is valued, we must always be vigilant to speak out against bad ideas. That's a civic duty whereby we continue to value free speech, freedom of the press, and the right to protest.
The idea that we can censure ourselves from bad ideas, however, by simply by telling pernicious, vile, and grotesque people to go away is underestimating the sensibility of pernicious, vile, and grotesque people.