"Neither of these [action in the Sudan or the Dodecanese] ought to detract from the supreme task of inflicting further defeats upon the main Italian army." (quoted in Correlli Barnett's The Desert Generals).
The Germans planned to go into Greece from Bulgaria, although not until March 1941. They were on a tight timetable, as the plans for attacking Russia in June were quite advance. To Churchill, defending Greece became more important than holding the gains in North Africa. He was ready to pull strong forces out of Libya and send them to Greece,w there they were expended, with only a portion being retrieved.