Citizenship and national origin are, as is immigration status (under different laws.) Also source of income.

Renting only to international university affiliates on particular kinds of visas is directly discrimination on the basis of all of citizenship, national origin, immigration status, and source of income, and might also constitute disparate impact discrimination (which California FEHA also covers as well as direct discrimination) on other protected grounds if the direct discrimination wasn't enough.

Yes it is, but it's impossible to enforce because landlords can ask for your drivers license/ID with the application and if you are on a visa your ID says "LIMITED TERM" on it. So they can always say yes or no based on that but pretend it was something else that made them make the choice.

Looks like immigration status is protected. I wonder if a plaintiff could win a case on the grounds that they were discriminated against because they weren't on a temporary visa.

As a former lawyer, I realize it's possible to make the argument, but it's probably clear from the legislative history of the law that it's meant to protect people who are on visas, not people who aren't.

Also, she would probably say that her rule is that she only rents to people who have an extremely compelling reason to leave after 1-2 years. Compelling reasons include time-limited positions (postdocs) or visa restrictions.

Answering my own question- it appears that yes, it is- https://www.dfeh.ca.gov/Housing/#whoBody