“Free speech” is inherently a slippery idea. Its essence is that the government can’t prevent you from holding opinions or from voicing those opinions in public. But it explicitly does NOT entail that anyone has to give you as much as a soapbox to stand on in making your opinions public. In this pretty open media age of ours, odds are that you can find some kind of media to make virtually any opinion public, but there’s no automatic right to such media for anyone. And of course there are the well-known exceptions such as the “shouting fire in a crowded theater”, as well as libel and slander laws.
Likewise academic freedom. As an academic, you are entitled to hold any opinions you wish, about anything – your students, your colleagues, your field, your university. And you are entitled to express those opinions in public. But your university isn’t automatically required to give you a class in which you can express those opinions to students, or to publish your opinions in the campus newspaper, or anything else. And under the current interpretation of labor law, unless you have some agreement to the contrary (such as a tenure agreement), they can terminate your employment at will and are not obligated to offer any explanation to anyone. This has been discussed a lot recently on some LinkedIn blogs (part of this is adapted from my comments there.)
So untenured people can and often do get fired for holding unorthodox opinions about lots of things, particularly if they express those opinions in public. To try to plead “academic freedom” as an exemption from these consequences would be tantamount to claiming that because you hold an unorthodox opinion about anything, the state is required to give you a medium for expressing that opinion. And, for free speech generally, that argument is over, and you lost. If the academic freedom argument were generally accepted, then all anyone faced with termination would have to do is find some particularly unpopular position and stake it out, thus acquiring immunity for life. I doubt that even the most rabid supporters of academic freedom would be willing to push the consequences of their position that far.
The legal fact is that the medium of the classroom is proprietary to the university; they make it available to you. That’s the difference between expressing your unpopular opinion in the classroom in front of the students and shouting it through the window while outside standing in the shrubbery. You seem to be interpreting the Twitter medium as a “common carrier”, obligated to carry any message entered into it by those able to afford the fee (which happens in this case to be nothing more than the possession of a device capable of connecting to the system). Now Twitter is not in fact a common carrier but a proprietary network, as is evident by its frequent taking down of messages and threads that become controversial; you can’t plead “free speech” in order to avoid their doing so.
There really aren’t any “common carrier” media for ideas; all media are proprietary in various ways. So-called “public media” like NPR or BBC are as strictly monitored and controlled an anything, generally more so, which accounts for their generally risk-averse attitude toward anything unorthodox. Those who long for the return of the “Fairness Doctrine” applied to talk radio might want to remember exactly how much interesting and provocative discussion there was on radio back when that doctrine was in force – in case you don’t remember, the correct answer is “none”. Radio stations were so afraid of being required to give “equal time” to anyone that they refused to broadcast anything that might conceivably provoke such requests.
Let me reiterate – I am NOT in favor of universities’ censoring opinions expressed by faculty in classes, but the fact is that since they own the medium they have that right unless some formal tenure or “academic freedom” covenant limits their ability to exercise that right. And in the case of untenured contingent faculty (now approaching 70% of all faculty), they have the absolute right to terminate employment at will. I don’t think that’s right either, but it is what we have let the law become. “Academic freedom” allows you to hold any opinion you wish, but it does not guarantee you an unlimited claim on the resources of the university to disseminate that opinion. Even the most senior tenured and respected academic isn’t automatically entitled to teach any class that s/he wants to; that’s always at the discretion of the institution.
You shouldn’t lose your job because you express an unpopular opinion in a class, or because you make some students uncomfortable by not having “trigger-warned” them ahead of time that they might read about violence against puppies, or because you criticize the actions of the Republican-controlled House of Representatives with regard to budgets and shutdowns in a class containing some Republican students. But the fact is that we live in a proprietary media society, where, as Yossarian was told, “Catch-22 says they have a right to do anything we can’t stop them from doing.” Institutions curtailing the expression of ideas may be acting unethically, but not, as matters stand, illegally.
Personally, I think it’s reprehensible that anyone would lose their job for expressing a negative opinion about their organization. But I don’t see that “academic freedom” as an argument can be extended to prevent this. Our understanding of free speech in general won’t sustain the claim.