Malcom X spent most of his life working for the Nation of Islam, which was a VERY violent and hateful group...
Define "very violent".
Virulently racist and 100% opposed to MLK's pacifist movement. While X never did, many of his brethren were abusive to their wives also.
The Nation of Islam was actually quite peaceful in terms of day-to-day behavior. It didn't encourage killing people, or having riots, or fomenting revolution. It awaited God's Judgment on Western civilization, yes, but that would be God's doing, not man's.
Eh, sort of. They encouraged the sometimes violent taking of the rights that belonged to African-Americans.
Now, if like Malcolm, you started speaking publicly about the inner foibles of Elijah Muhammad, sure, that could get you into trouble.
X had encountered true non-racist Islam in Mecca, and began to call Elijah out about it. Truth is, the Elijah-bashing wouldn't have started without X's conversion to a non-political Islam.