The above sentence is essentially lacking entirely of meaning. As your right of speech/expression can only be invoked when suppressed by a state entity, I assert that a non-state actor cannot possibly violate said right.
Please give me one example of a non-state entity violating your right to not have your speech oppressed by the state?
How does my right to free expression require a state entity? That implies that right is provided for by the state entity. That's not how it works.
Here's an example of how a non-state entity can violate your right to free expression with the state's approval; you start to say something I don't like, I punch you in the face to shut you up. You try again and I punch you again. Now imagine a police officer standing right next to me watching me do it.
I suppose I interpret the title "The Universal Declaration of Human Rights" as meaning beyond government oppression. I believe in the idea of natural human rights and government exists because we allow it.
Regardless, I interpret government inaction on non-state actors that actively suppress by illegal activities a person's rights to free expression (or speech, whichever makes people happy) as a form of government oppression.
EDIT: thanks for the discussion, you've given me much to consider.