IMHO, Cornel West makes the point Ollman tries to make far more directly and clearly, and draws the right conclusion: Ethics are real, but history is the context, so there is always more to be learned, and humility is required.
Meanwhile, I stand with Erich Fromm's reading of Marx:
"[T]he very aim of Marx is to liberate man from the pressure of economic needs, so that he can be fully human...Marx is primarily concerned with the emancipation of man as an individual, the overcoming of alienation, the restoration of his capacity to relate himself fully to man and to nature....
"Marx's philosophy constitutes a spiritual existentialism in secular language....
"Marx's aim, socialism, based on his theory of man, is essentially prophetic Messianism...."
"Marx's central criticism of capitalism is not the injustice in the distribution of wealth; it is the perversion of labor into forced, alienated, meaningless labor, hence the transformation of man into a 'crippled monstrosity.'"
_Marx's Concept of Man_, 1961, pp. 5, 42.
"Communism...is humanism." -- Karl Marx