Since the University of the Antarctic is in the Antarctic, I am not sure what laws would apply to it. But we'll assume that US Law applies since it is being run by a US Citizen.
Currently, since there is no case law that applies to Section 508 of the Reauthorized Rehabilitation Act, it is unclear how far this law will reach. Most seem to believe that it will eventually have a similar scope as the Americans with Disabilities Act (ADA), and affect all US web sites. For now it would appear that only US Government web sites are required to conform to that particular law.
Section 504 seems to be more applicable, and if the University of the Antarctic receives any US Federal money, it will need to have an accessible web site based on the anti-discrimination language regarding those students with disabilities.
Also untested in the courts, is how much legal weight the Harkins letter holds with regard to Web accessibility and the ADA.
Taken together, it would seem that all web pages on the University of the Antarctic site should be accessible. Even without the Federal regulations, it is still the right thing to do.
The most compelling law for states is the American With Disabilities act. Taken together with the Harkins letter opinion, although untested, provides a good reason for all states to require their web sites to be accessible.
As a developer tasked with creating an online tax process for filing state returns, I would disagree with the idea that I wouldn't need to worry about accessibility. One of my arguments would be that creating an inaccessible site for this purpose would be like begging for a lawsuit to be filed. I am sure that there are those who are interested in testing the Harkins letter/ADA as it applies to states and their web sites. A high profile site like this would be the perfect test of such a law.
As such I would strongly recommend that every effort be made to make the site accessible, and that we would work with disability related groups in developing and testing the site so that the site would be a showcase of how to do it right, rather than a test case.