The right to freedom of expression is recognized as a human right under Article 19 of the Universal Declaration of Human Rights and recognized in international human rights law in the International Covenant on Civil and Political Rights (ICCPR). Article 19 of the ICCPR states that "[e]veryone shall have the right to hold opinions without interference" and "everyone shall have the right to freedom of expression; this right shall include freedom to seek, receive and impart information and ideas of all kinds, regardless of frontiers, either orally, in writing or in print, in the form of art, or through any other media of his choice". Article 19 goes on to say that the exercise of these rights carries "special duties and responsibilities" and may "therefore be subject to certain restrictions" when necessary "[f]or respect of the rights or reputation of others" or "[f]or the protection of national security or of public order (order public), or of public health or morals".
Having a chat ban is clearly going against these laws. A person can individually mute a person via the scoreboard menu, there is no need to revoke the "privilege' to speak universally.