By threatening the sacrifice of Mecca in retaliation for any further Islamist terror, Islam would hopefully be pressed to identify one leader to speak for the religion and denounce all forms of terror, especially terror inflicted in the name of Allah. Then, the leader could convene a reformation clarifying the Koran's position that terror, and spreading the religion by the sword, are intolerable. If this doesn't happen, we're going to end up picking them all off one by one after a sufficient number of us infidels die.
The problem is that the Koran's position is that terror and spreading the religion by the sword are perfectly legitimate. These people are basing their actions on the words of Mohammed in their scriptures. Sadly, the violent ones are the orthodox ones.