The debris will likely miss due to the evasive maneuvers both the missile and the target did, and due to the lack of thrust after the destruction of the missile

The debris will likely miss due to the evasive maneuvers both the missile and the target did, and due to the lack of thrust after the destruction of the missile. Plus the standard practice seems to be pointing the main engine (with exhaust velocity measured in percent of light speed) at the approaching missiles. To avoid being vaporized, the missiles must be intentionally trying to miss and then do aggressive last-moment maneuvers once they are close enough to the target.