The multipolarity of the Islamic world is a problem indeed. There are not just Muslims: there is the Sunni and the Shia variety, and from there on, it gets complicated. A bit indeed like the Christian churches that are not even begun to be described by calling them Orthodox, Catholic or Protestant - there is no man who is considered a supreme authority by all of the denominations. To put it a bit bluntly: the Holy Trinity can be agreed upon, but beyond that it starts to get fuzzy. And indeed, there are Christian denominations that are
highly offended by things like a pork roast dinner that is very normal to others.
But of course, there are persons within Christianity that have somewhat higher authority than others. Even though not everyone will follow the Pope´s teachings to the letter, he will at least be listened to by many. About the same, but to a slightly lesser extent, can be said for the Archbishop of Constantinople, who is heard in most Orthodox churches.
And the same can be said for Islam. If the al-Azhar University of Cairo speaks, it will be heard by many Sunnites. To get back to the abominable murder that was the cause of this thread - it seems indeed that the Grand Imam of al-Azhar Mohamed Ahmed el-Tayeb has spoken, highly condemning this and calling for most severe punishments to be inflicted on the murderers.
One will wait to see where this leads to. The roots left aside (as discussing them is only of academic interest and the present situation is a given fact); it is however clear that cleaning up this mess is an intra-Islamic problem that cannot and will not be solved with Western, Eastern and other non-Islamic involvement - as has been said by several other posters on here.