From a constitutional perspective (which is the perspective Supreme Court Justices swear to have), the ability of the government to limit speech is not allowed. Full stop. Sources below.

First Amendment to the Constitution: "Congress shall make no law respecting an establishment of religion, or prohibiting the free exercise thereof; or abridging the freedom of speech, or of the press; or the right of the people peaceably to assemble, and to petition the Government for a redress of grievances."

Constitutional Oath taken by all current Supreme Court Justices: "I, _________, do solemnly swear (or affirm) that I will support and defend the Constitution of the United States against all enemies, foreign and domestic; that I will bear true faith and allegiance to the same; that I take this obligation freely, without any mental reservation or purpose of evasion; and that I will well and faithfully discharge the duties of the office on which I am about to enter. So help me God."