It's a difficult situation to be sure. But, the corruption isn't just with Mugabe but with the entire Government.
What could we do? Even if we (the UN?) had sufficient forces to invade and occupy yet another Country what could we do then? Who could we leave in charge and would they be any better than Mugabe.
Don't misunderstand me, I'd love to see a change over there and the situation is truly terrible. But, I don't see what we could do that wouldn't make the situation worse.