i don't know where you got that from wikipedia said that Martin didn't wanted to be assosiated with communism.
he speech was a reflection of King's evolving political advocacy in his later years, which paralleled the teachings of the progressive Highlander Research and Education Center, with whom King was affiliated. King began to speak of the need for fundamental changes in the political and economic life of the nation. Toward the end of his life, King more frequently expressed his opposition to the war and his desire to see a redistribution of resources to correct racial and economic injustice. Though his public language was guarded, so as to avoid being linked to communism by his political enemies, in private he sometimes spoke of his support for democratic socialism. In one speech, he stated that "something is wrong with capitalism" and claimed, "There must be a better distribution of wealth, and maybe America must move toward a democratic socialism."
King had read Marx while at Morehouse, but while he rejected "traditional capitalism," he also rejected Communism because of its "materialistic interpretation of history" that denied religion, its "ethical relativism," and its "political totalitarianism."
Does this make him a communist? very interesting.