The moves themselves tell a story even without an official explanation, and reading that pattern is worth doing carefully.
The honor farm is the best housing situation available in most county systems. It is reserved for inmates who have earned a lower custody classification, typically through good behavior, a nonviolent record, and a clean institutional history. Getting placed there initially means he qualified. Getting pulled from it means something triggered a reclassification, and facilities do not move people off the honor farm without a reason.
The back and forth between the farm and the pods suggests the situation is not fully resolved one way or the other. If a disciplinary infraction had been clearly established, he would likely have stayed in higher custody. The movement pattern points more toward an ongoing investigation, an unverified accusation, or a court-related logistics issue that required a temporary housing change. All of those can result in someone being shuffled around while the situation gets sorted out.
The move to jail core is the most significant development in that sequence. Jail core is general population at its most basic level, a step down from the farm in terms of privilege and comfort. That placement suggests either a classification decision has been made or something more concrete has developed.
Here is the honest part of this answer. It is genuinely hard to believe he has no idea what prompted any of this. Inmates almost always have some sense of what is happening around them, even when they have not been formally told anything. Whether he is protecting you from a difficult conversation or genuinely in the dark, the most direct path to answers is for him to request a meeting with his case manager and ask directly what his current classification status is and what triggered the changes. He has a right to that information.