Toad, if your reasons were used by the US government, the US would have been all over Africa by now. And Latin America, and...well, the US would be fighting on every continent except possibly Australia.
It's BS to say the US does this solely for altruistic reasons. It might be part of the reason, but it isn't the important bit. If it was so important, why wasn't something done in Rwanda? Why not in other places today?
Freedom argument is well and dandy, but reality check please. It is secondary to other concerns and the world as it is today proves that. I hope I do not need to show this, but I can.