Well they are "missiles" not "hittiles", and designed for a near miss so that the warhead chops the plane in half, rather than hitting the jet pipes etc. With the proximity fuses disabled a hit is a misfortune rather than a success.
I'm just bemused at the self-destruct excuse, I thought the telemetry was used to show how close they came, and the self-destruct was that built in regardless to ensure no blue-on-blue fratricide if they missed the planned target.