Could you clarify what you mean exactly with this. In my mind people should have a right to ignore speech they don't want to hear. Furthermore, the definition of a "platform" has become very diffuse with the advent of the internet. In the before times you were either in the newspaper most people read, or maybe on one of the handful of TV channels, or you basically did not have a platform beyond the people you could physically interact with. Whereas now you can have many options which all reach different kinds and amounts of people.
I have many vague feelings but maybe I can sum them up in the following, probably unhelpful, statement: people have a right to a platform that is equivalent to standing in a town square and yelling.