If the record of what a system decided is mutable or optional, every attestation built on it is unfounded. Memory in a governed system is not storage you read back later — it is the control surface the enforcement plane writes to in-path.
Most systems treat memory as a store: a place to write things down and read them back. In a governed system, memory is something else — the surface on which the enforcement plane records what it admitted, why, and under whose authority. If that record is mutable, or written after execution as a convenience, it describes the past without constraining it.
A decision record that can be edited is not evidence; it is a note. Runtime governance requires the record to be produced in-path, as part of the decision that admitted an action, and immutable once written. Memory then stops being a passive log and becomes a governance surface — the thing every downstream attestation actually stands on.