Every religion has their own sects. Although the term is somewhat pejorative nowadays, its meaning is still applicable. Christianity, for example, has Catholicism, Protestantism, and the LDS church. There are several sects within each of those major categories. It really wasn't to long ago that Catholics were still heavily persecuted within the United States.
Buddhism has several different "schools" within it, as does Hinduism. Yes, even Judaism has several sects. Heck, even the atheists have different "schools" of thought such as the "New Atheists" and the lower-case 'a' atheists, and apologists ("Can't we all just get along?").
So we should not be surprised that Islam has its own sects. Some of the names are quite common to those who have paid any attention to the Iraq war. Sunnis and Shiites are the most commonly heard. There is one sect of Islam called Sufi. Apparently, one of the men behind the Manhattan Islamic Cultural Center is from this sect. From what I can tell, they are big into mysticism and love and not so much into the dogma that is often characteristic of Islam. They sort of sound like the Islamic version of hippies.
Last month, a Sufi shrine was the victim of radical Islamic suicide attacks in Pakistan. If this is indeed the leanings of this cultural center, they seem like a long shot in being supporters of those that killed dozens of their own in Pakistan.
But demagogy tends to make one overlook details such as this.