Comments about the first amendment are very true, that offensive speech is not in of itself actionable via the first amendment. To some of the kind who wear their patriotism on their sleeve, burning a flag is tantamount to declaring war on the US, to someone like myself it is a stupid act that won’t do anything, but I firmly believe it is covered by the first amendment. Some people think that erotica and porn should be banned, because it is offensive or because their Bible tells them so or whatever, but again, it is the first amendment. And I absolutely agree that the first amendment has to be given serious weight, it cannot be overridden arbitrarily.
And like all first amendment issues, it is not always clear cut, as pointed out with incidents at the Cal State schools versus what happened at OU, where Muslims yelled “Allah Akbar” at Jewish Students (with said words having direct ties to terrorism, the 9/11 terrorists used those words when they crashed the planes on 9/11) and nothing happened, it is always open to interpretation.
However, to argue that physical harm is the only harm and the first amendment applies to anything except where physical harm happens or could happen (yelling fire in a movie, incitement to riot) is not correct. Clarence Thomas pointed out that cross burning is not covered by the first amendment, because the burning cross is a symbol of intimidation, it is not a bunch of drunk white guys having some fun, that the intent is to threaten anyone the Klan doesn’t like, and given the Klan’s long history, it is not an unreasonable one (and in that guise, the Muslim Students in California should have been censored IMO). On the other hand, the student who said the flag to them represented repression, and said the flag should not be flown, is making political speech, no group is singled out, there is no implied harm, it may be an unpopular position, but no one is harmed other than those who fetishize the flag beyond what it is, who think the flag itself has some magical properties…
With schools, public (and obviously private) the first amendment can be tempered by other factors that may not seem relevant but are. For example, if they feel the actions of the frat boy morons hurts the image of the school, they may have grounds to act, if being admitted to the school the student agrees to a code of conduct towards fellow students, and if that violates that, it could be considered a breach of their right to be there, first amendment or no first amendment, if there is justification for suppressing the speech. Does what the idiots did in this case justify expulsion? If the university argues that their actions cause harm to the school, if there is something they can convince a court of, then the first amendment doesn’t apply, because the need of the school can override it. Likewise, while public employees enjoy some free speech rights private employees do not, if an employee of the post office made public statements badmouthing their boss, or the heads of the postal system., or if for example they made racist remarks about patrons of the post office, they could be fired, their right to free speech is limited, even though the post office is considered a government agency (well, bounced back and forth, but I believe it still is). Speech that is detrimental to a public work environment in how it functions is not covered, and speech that disrupts a campus, or otherwise interferes with how it does business, could and has overriden the first amendment. With any right, there are always limits, and what it generally comes down to is that those who act against the first amendment have the burden to show that their actions were for a legitimate reason, and the bar is pretty high, but it does exist, might be higher or lower depending on the place and time, but it is there, the first amendment is neither absolute nor all binding, nor is it necessarily well defined.