Precisely this. I find it appalling that an associate professor was not given tenure, because that is normally a tenured position, particularly since he'd been there 20 years
I think he was an Associate Professor of the Practice -- it's not a tenured position, but more a longer-term teaching-type appointment. It generally offers more job security and benefits than an adjunct might receive, but at many universities such a position is not (and was never) on a tenure-track line.