Full disclosure: I am a Roman Catholic, and I put this whole account up to pure rumor.. Catholics administering the Temple Mount, while far from ideal from an observant Jewish perspective, is inarguably better than Muslims administering it. However, the Catholics administering it should come from an international panel of the Church and should not be selected from local clergy, since local clergy can be pressured by the Muslims who outnumber them so vastly. This is the first I've heard of this specific proposal, but the Vatican has previously offered the initiative of Jerusalem becoming an international city, administered by Christians, Jews, and Muslims. The Israelis have already rejected this offer, and I doubt any muslim would agree, except as part of a stepping stone to full control.