SOP back in those days. I have no direct knowledge of the operation you speak of, but we did the same thing in various places of the world. Usually the justification was to fight communism. Cuba, Chile, Phillipeens, ROK, and a host of others all pretty much had a dictator/military junta-type government that was backed by the USA at one time or another. The CIA was famous for organizing take overs of other countries that would end up with a friendly government. "He may be a tin-horn dictator, but he's our tin-horn dictator" was a familiar spoof phrase on the situation back then. As long as they weren't communist and we had an advantageous position, we really didn't care two cents what went on in other countries. Kinda the same thing China does today. Back who they need to for their own agenda, and not really care too much who it is or what goes on inside that country.
You pretty much have to place it in the overall cold war context. It was all about fighting the enemy back then. So anything you did to stop the "red menece" was free game. Anything that goes on in the Middle East is fueled by oil in the end. When you look at a map and see how close the old Soviet Union was to the main source of oil for Europe, and even the USA, you can see why you don't get an outcry from the more "cultured" nations of the world either. They knew it had to be done to not upset their apple cart and they were just as happy we were doing it as anyone could be. Back in those days alot of countries would make some noise about it, but secretly be patting us on the back for doing it. Much of our relationship with Saudi Arabia, and the pre-positioning/base use capability, that we used in Desert Storm, and still use today was based on the Soviet Union making a move into the Middle East and the US having to respond to it. Having friends with an iron grip in charge in those countries that actually shared a border with the old Soviet Union was far more important than if an ethinic group was being treated fairly.
It just the way it was back then.