Notice he was an adjunct professor. Adjunct means he wasn't a full-time employee--he had year-to-year contracts, probably without health care. He might have his contract renewed next year; he might not, and have to find someplace new to live.

No wonder he was depressed: he was gifted, spent years of his life in squalor to get a PhD, and then found himself an adjunct in his 70s. He got paid about half as much as full-time teachers, taught more classes, and had to teach the classes nobody else wanted.