A microphone is a resource: who gets one?
The freedom to speak and a claim to an audience are different questions.

A public institution invites one speaker and declines another. Is that ordinary selection, unfair exclusion, or censorship? The answer depends partly on what the institution promises, who controls it, and why it made the choice. An unlimited principle sounds simple until someone must allocate a finite room, budget, and audience.
Name the institution
A private reading group, a public university, and a national broadcaster do not have identical purposes. A useful debate begins with the responsibilities of the particular institution. It should also distinguish a refusal to host from an attempt to prevent a person from speaking anywhere.
Apply the rule to opponents
A selection rule gains credibility when it can be applied to speakers its authors dislike. If the rule is relevance, show how relevance is assessed. If it is a credible risk of disruption, explain the threshold. Vague appeals to controversy can become an easy way to avoid difficult ideas.
Leave room for criticism
Hosting a speaker need not imply endorsement, and protesting an invitation need not imply opposition to all expression. The difficult boundary concerns conduct: challenge, disruption, exclusion, and intimidation have different effects. A clear policy should protect debate while making those distinctions understandable before a dispute arrives.
Bring your perspective
What obligations should a publicly funded venue have toward unpopular speakers?
Start a debate