There will always be a normative component to our behavior (we should act to the interests of the proletariat as a class, in the goal of revolution to abolish commodity production and property and overturn the law of value, rather than be guided by moral principles), but even for moral principles human rights is pretty bad for our interests. Marx isn't saying "go and starve and torture a bunch of people", but that doesn't rely on human rights. Morality in general is superstructural and is based on the class structure and mode of production of the time, but human rights specifically assumes atomized individual man and evolved most definitively with capitalism and liberalism, so this text was specifically critiquing one very historically limited application of morality. Rights have existed for longer, and are also superstructural, but not in the human rights sense.