I don't understand what this means either. "In theory, if everyone played by the same rules"? Everyone doesn't have to set the same rules, that would go against freedom of speech. Corporations have the freedom to set the rules for their property as they like. And they also get to enforce those rules as they like, as long as failure to enforce does not cause law breaking to happen on their property (for example, copyright).
I don't understand what this means either. "In theory, if everyone played by the same rules"? Everyone doesn't have to set the same rules, that would go against freedom of speech. Corporations have the freedom to set the rules for their property as they like. And they also get to enforce those rules as they like, as long as failure to enforce does not cause law breaking to happen on their property (for example, copyright).