The answer to this question is complicated by some unique academic rights enjoyed by faculty under the general concept of academic freedom. Academic freedom is generally considered to mean the right of faculty to speak freely on political and ideological issues without fear of reprisal. However, it commonly is thought to also encompass the right of faculty members to teach in the manner and style of their choosing. So, for example, a faculty member may state that they are under no obligation to design a website using accessibility guidelines any more than they would be required to teach using a particular methodology or give a certain type of examination.
Although there has not been a court decision or OCR ruling on this issue, using academic freedom as a justification for maintaining an inaccessible website would probably not be considered a sufficient defense. It is clear that if the website is available to students and a student enrolls who cannot access the website, the information on the website must be available (that is, the information must be "effectively communicated").