And yet Marx himself was not, himself, a despot or murderer. He was probably a pretty nice guy. Your description is therefore similarly incomplete. He can be both things. History is complicated, and not well served by summary arguments.
Thomas Jefferson did almost exactly the same thing. As did Nelson Mandela.
There's a pretty big moral space between advocating the overthrow of a government and the behavior of a Stalin or Pol Pot. Marx belongs to the former category, not the latter. But because of events that happened decades after his death, he's remembered as something he wasn't. His crime was being wrong, not evil.
And yet Marx himself was not, himself, a despot or murderer. He was probably a pretty nice guy. Your description is therefore similarly incomplete. He can be both things. History is complicated, and not well served by summary arguments.