He didn't say "Communism is great, let's all hold hands and dance in a circle around a big red star"; he said, "Marx claims capitalism and other systems have some flaws." There's a big difference between the two statements.

Your knee-jerk reactionism betrays you. Marx is capable of having some good--or at the very least, thought-worthy--points amid an ultimately flawed solution (communism). For you to dismiss a point by painting it with a "red menace" ad-hominem (not your words, but certainly their spirit) is, too, dangerous thinking--or perhaps lack of thinking.