Probably his best Constitutional defense would be California's Constitution's Article 1, Section 2:
(a) Every person may freely speak, write and publish his or her sentiments on all subjects, being responsible for the abuse of this right. A law may not restrain or abridge liberty of speech or press.
(b) A publisher, editor, reporter, or other person connected with or employed upon a newspaper, magazine, or other periodical publication, or by a press association or wire service, or any person who has been so connected or employed, shall not be adjudged in contempt by a judicial, legislative, or administrative body, or any other body having the power to issue subpoenas, for refusing to disclose the source of any information procured while so connected or employed for publication in a newspaper, magazine or other periodical publication, or for refusing to disclose any unpublished information obtained or prepared in gathering, receiving or processing of information for communication to the public.
Nor shall a radio or television news reporter or other person connected with or employed by a radio or television station, or any person who has been so connected or employed, be so adjudged in contempt for refusing to disclose the source of any information procured while so connected or employed for news or news commentary purposes on radio or television, or for refusing to disclose any unpublished information obtained or prepared in gathering, receiving or processing of information for communication to the public.
As used in this subdivision, unpublished information includes information not disseminated to the public by the person from whom disclosure is sought, whether or not related information has been disseminated and includes, but is not limited to, all notes, outtakes, photographs, tapes or other data of whatever sort not itself disseminated to the public through a medium of communication, whether or not published information based upon or related to such material has been disseminated.
If the Constitution doesn’t apply to state or local governments, there would still be slavery.
The Supreme Court, interpreting the protections of the Fourteenth Amendment broadly, have recognized that not only are people protected from abridgment of their freedom of speech by Congress, but are also protected from abridgment by state governments as well as creatures of the state such as cities and counties. This would include publicly supported colleges.
The idea of "free speech zones" suggests that there must also be "prohibited speech zones". Not a good idea.
In support of his case, the student should arrange to have someone passing out pro-abortion or anti-Trump literature under the same circumstances. It wouldn't surprise me a bit if this strengthened his case considerably.
“To be fair, the First Amendment says nothing about state/local governments, privately owned businesses, or even the executive or judicial branched — it applies specifically and explicitly to the Congress.”
You are very off base. The first amendment does not only apply to congress. Where did you get such an interpretation? The body of law arising out of the 14th amendment has indeed made the states subject to the 1st amendment.
For about the last 100 years the bill of rights has been applied to the states. Also, this “private” institution is probably taking all kinds of federal money. That comes with strings. Free speech zones won’t stand. Also, the justice department is no longer the friend of such radicalism as free speech zones.
Given the various interpretations of the Constitution which we commonly see, we would be living in anarchy if there wasn't a way to "settle" issues with interpretation in a way which prevents civil war every time factions disagree.
For the most part I think our nation has done pretty well despite the limitations of a two hundred year old Constitution. Had Hillary won the election I wouldn't feel nearly as good about it.
Stop giving these leftist colleges and universities money.