It took us quite some time to get everything up in a way that would work on most Purdue systems and our own personal ones and from there even translating the limited codebase we were using unsafe code blocks for nearly everything (and ASM blocks) and some internal code for multicore/ACPI-related things/Galileo boards we haven't made publicly available yet, AFAIK.
At the end of the day, Xinu was small enough and very concisely written and maintained for several decades that switching to a language like Rust wasn't warranted. Similar to sqlite, I suppose. You can email me at [email protected] if you'd like to know more details/talk to Dr. Comer about Xinu things.
(I'd love to see OS classes use Rust someday, so I'm always trying to keep an eye out for things...)