If it was white people raping blacks, there would be outrage. Why? Rape is wrong. I think all sane people can agree with that.
But once one enters this never-never land of leftist ideology, nothing is any longer wrong if SOMEONE OBJECTS. All you have to do to stop a sybaritic leftist is accuse them of insensitivity. They have no place-holder for justified violence, for self defensive violence, for violence in the name of principle, in the name of decency. They cannot justify blaming this epidemic on Muslims, and cannot justify asking them to either behave or leave, which is quite obviously within their rights.
And if they fail to do this, they will fail as a Liberal nation. They will fail as an advanced nation. They will fall, of their own free will, to primitives. They will demonstrate, in the end, that they believe nothing.
Perhaps the salient difference between a Sybaritic Leftist and a full blown Cultural Sadeist is the extent to which the latter creed is infectious. The first is not living, and the second is an aggressive flesh eating zombie.
All of these myths–the zombie, the vampire, the werewolf–address important sociological realities.
Liberalism is possible. It is both possible and desirable to reconcile cultural and social differences, peacefully, through shared understanding. But you cannot do that with primitives who insist on imposing their vision of the world on you. You cannot negotiate with people who do not WANT to negotiate. That is why wars and violence will be needed at times until all of humanity grows up.