I disagree. He was the paid mouthpiece, sure, but, it was his works that led to others being able to leverage his BS to kill more people than anything else in modern history that I'm aware of.
Discussion
Marx had been dead for decades when the people learning on his works did their foul deeds.
Also, paid mouthpiece? For whom?
Decades don't matter to some people.
For the powers that should not be. I'll sound really nutty if I go into it too much, but, Marx was not acting on his own and was just another piece in a leather puzzle to enslave all of mankind.