If a university press decides to publish a manuscript, should the author have a literary agent?
Remember that I am a literary agent so I think every author benefits from being repped by a good agent.
However. What you're really asking here is if you (or anyone) can navigate a contract or a publishing relationship without an agent and the answer is yes you can.
I've posted before about some of the things to do.
For university presses, you want to be VERY careful about copyright. Make sure they do not register the copyright for your work in the name of the university. I've seen this happen more than once and it seems to be the standard opening gambit on many contracts.