It's not "absurd" -- it happens all the time. The Red Purge, for instance. Neither academic freedom (thought to be enshrined in tenure) nor the First Amendment protected the Reds when the political tide turned in 1947. The SCAP censored the media, textbooks, etc. while it occupied Japan also, first targeting fascism, then targeting socialism or anything smacking of socialism, to say nothing of criticisms of the SCAP.
Based upon historical evidence, I conclude that whether a given speech gets protected depends mainly upon (1) whether its content threatens the powers that be (in reality or in the imagination of those who hold political power) or (2) whether the masses rise up to defend the speech or the person who utters the speech in question.
Yoshie