MLK was not a "nicer guy" in the context of completely bowing down to whites. That is a myth and a terrible one. He had guns and understood that it might be necessary to use lethal force for self defense, including employing armed defenders. He understood that, as other posters pointed out, his message and terms needed to be presented along side a very counter-revolution and violent alternative.
Malcolm would end up walking back a lot of what he said about MLK later on in his life.
fukk what you heard, MLK was the greatest American that ever lived. Not only did he contribute to the Black Civil Rights movement, but was the most prominent advocate of social justice, socialism, anti-capitalism, love, integration, and legal political morality that has ever existed in this country. And to be honest, that's why I think they killed him. Once you start advocating and showing people the atrocities of the Military Industrial Complex and Capitalist greed, that's the end of the line, especially back in those days during the Cold War and the US Government's systematic blow back to Socialist and Marxist policies.
All in my opinion of course.