According to Malcolm X, what are "Uncle Toms" and how do they slow progress for blacks in America?

Malcolm X believed Uncle Toms were black people that were very obedient to white people or used by the white man to keep other blacks "in check". He stated "Just as the slavemaster in that day used Uncle Tom to keep the field negroes in check, he was the same old slavemaster who today has negroes who are nothing but modern Uncle Toms - 20th-century Uncle Toms - to keep you and me in check." He believed Uncle Toms slowed progress for blacks in America due to the fact of integration. Malcolm X believed that blacks and whites should stay away from each other and not integrate as he stated "You don't integrate with a sinking ship." So Malcolm X saw it as if blacks were integrating with whites then no progress will be made due to the fact that black separatism (blacks creating separate institutions / not integrating) was not being practiced.