Yes, the Complex Detention Unit is segregation housing. But there are two distinct reasons an inmate ends up there, and they are not the same thing.
Disciplinary Segregation is what most people mean when they say the hole. It is a punishment imposed for breaking prison rules, and it is meant to be short-term. An inmate gets written up, goes through the disciplinary process, and gets sent to the CDU for a defined period. It is reactive, meaning something happened first.
Administrative Segregation is different. It is a housing decision based on classification rather than conduct, at least in theory. The Arizona Department of Corrections assigns every inmate a security score between 1 and 5, with 1 being minimum security and 5 being maximum. That score is calculated based on the nature of the offense, criminal history, institutional behavior, and perceived threat level to the public and to the facility. When the score warrants it, or when there are safety or management concerns, the department can place an inmate in administrative segregation without a disciplinary infraction triggering it. The DOC has broad discretion over these decisions.
Seven moves in under six months, six of them within the Tucson complex across different yards, is a pattern worth paying attention to. That kind of movement usually signals either ongoing classification adjustments as they figure out where he fits, conflicts with other inmates requiring separation, or behavioral incidents generating disciplinary action. Manzanita CDU as the current landing spot suggests his score or his situation has not stabilized yet.
The most useful thing you can do right now is get clarity from his case manager on whether this is disciplinary or administrative, because that determines what his path forward looks like and what he needs to do differently if anything.