Muslims believe that Muhammad (tgp) is the best example for all Muslims to follow. The Quran tells them so. So they cannot let something like Muhammad's genocide of the Medina Jews reflect badly on Islam or Muhammad. So, their religion compels them to support Muhammad's genocide.
This manifests itself in a variety of ways. For example, every Muslim who has posted here has attempted to excuse Muhammad's genocide by claiming that the three large Jewish tribes of Medina were party to the treaty of Medina and that each successively violated it, thus being to blame for their own genocide. This story appears to be a recent fabrication and Muslims refuse to discuss it's origin.
http://www.ozpolitic.com/forum/YaBB.pl?num=1543103591Gandalf has been even more creative in coming up with ways to support genocide, trotting out such classics as:
* tough titties, off with their heads
* they were literally a mindless collective of treacherous Jews without an individual personality
* only the warriors were executed (Muhammad identified the warriors with a genital inspection)
* the Jews made it up
* it is perfectly reasonable to deny the genocide happened, or attempt to downplay its extent, at the same time as supporting the genocide
* if wikipedia gives an example of a historian who thinks the treaty was actually a unilateral declaration by Muhammad, and that the copies of the treaty we have today list all the party tribes (the Jewish tribes are omitted), the only reasonable way to interpret this is as wikipedia claiming that not a single other historian in the world reaches the same conclusion