In this country, the First Amendment guarantees freedom of expression, regulating only time, place and manner of expression. Prior restraint is a violation of a person's First Amendment rights and is (almost) never justified. Okay, maybe publishing top secret government material is an exception, but that is not really what we're talking about. Prior restraint is usually only used to prevent people from hearing another side of an issue and taking an opposing side. For that reason, it is not justified.
It is unconstitutional for the government to deny the right to publish any document written by an American citizen regardless of the details of such publication. The right to publish is connected to the right of freedom of speech; they may express themselves with any intent they may wish to. The government may not like the contents but that is their right as well to disagree, just as much as to agree.