Section 11. Whoever by speech or by exhibition, distribution or promulgation of any written or printed document, paper or pictorial representation advocates, advises, counsels or incites assault upon any public official, or the killing of any person, or the unlawful destruction of real or personal property, or the overthrow by force or violence or other unlawful means of the government of the commonwealth or of the United States, shall be punished by imprisonment in the state prison for not more than three years, or in jail for not more than two and one half years, or by a fine of not more than one thousand dollars; provided, that this section shall not be construed as reducing the penalty now imposed for the violation of any law. It shall be unlawful for any person who shall have been convicted of a violation of this section, whether or not any sentence shall have been imposed, to perform the duties of a teacher or of an officer of administration in any public or private educational institution, and the superior court, in a suit by the commonwealth, shall have jurisdiction in equity to restrain and enjoin any such person from performing such duties thereafter; provided, that any such restraining order or injunction shall be forthwith vacated if such conviction shall be set aside.