Regarding the terrorist theory, whether or not the passport was false/stolen, it is not obvious how such a person could have created an explosion large enough to have knocked out all power simultaneously. That did not happen at Lockerbie, and the falling elements were large enough to have radar traces.
However, the instantaneous break-up and power-loss did happen with the Air Italy DC-9, thought to be a missile explosion close to or inside the airframe. Again, detailed examination of radar traces helped the theorists to focus in.