I would call that Bioengineering. It's also very closely related to Bio-mechanical Engineering, the line is very fine in the SAOverse, after all, the transhumans are part machine too in a way, so there is a lot of similarities between them and a suit of powered armour with biological components.
Bio-Engineer/Bio-Mechanical Engineer/Bio-mechanic/Geneticist/Molecular Biologist all works.
From the looks of things in a systemwide perspective, I think the "Xenobiology" might end up being a "General Education" course where graduates would learn the general points of all species then specialize into specific species same as the current day "Doctor" ends up specializing in specific fields (Urology, Oncology, Cardiac, ENT etc) after his basic medical degree.
As for how he's going to end up in the Ryujo, I'm not really sure how to fit. I mean weapons projects are multi-year affairs with scads load of testing and paperwork, not done in a scout ship sent to probe the outer edges of the known universe (unless he really pissed someone off). The facilities on board are limited to Yamataian derived life forms and haemosynth and I have my doubts as to the suitability of the ship's computer to be used as a biological mainframe and bio-informatics system since it was programmed to be a military machine first and foremost. Not to say it can't be done, the facilities can recreate entire Nekovalk, so construction should be a piece of cake, but design and experimentation on totally alien life forms? Not to mention is the CO willing to let you use up so much resources in testing and experimentation?
I don't see it unless he got orders from the back door asking to support some Black project with his scouting run as cover. Which is also possible.