I think it is very important to realize that he who formulated the ideas about Idi Amin being a further fullfillment of prophecy was alive during the time that Amin was around and it fit well with the one's interpretation of the situation after Selassie was the head of the O.A.U.

If one believes in prophecy, it is very easy to formulate a chain of events as being mystically tied. Some even believe Bin Laden is some kind of figure who was prophesized (whether good or bad).