Why was it ok to deal with Gaddafi in 2004 (ie the Blair oil deal), but today he is a madman that must go?

In 2004 Gaddafi was not killing his own people. However I do believe that the west only stepped in because of oil. I do not believe it has anything to do with protecting the rebels in Libya. If governments were so concerned about civilians dying at the hands of a dictator, why then did they not go for Mugabe when he clearly set about the genocide of his countries people? The answer is that there is no oil in Zimbabwe.