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.