If you go into a startup and say "I'm a communist," many of them are going to be pretty skeptical of your ideas. You will find yourself in a lot of awkward conversations if you make this a thing you want to talk about.
If you pitch a VC and throw in "btw, I'm a communist," or they find your online writings about being a communist, you aren't getting a check.
If you apply for upper management at Google and you say "I want to overthrow capitalism because I'm a communist," you're going to have a really, really hard time.
I don't think it's arguable that communists are actively operating in America and causing capitalists to have longer jail sentences or killing them when they wouldn't kill communists. So, no, I don't think communism is a threat whereas anti-semitism and racism are immediate threats.
I don't think that we need to jail all people who are racist, but I think it's just fine to not talk to them or to yell at them or even to fire if they feel the need to express their beliefs in a way that gets in my business or stops me or my team from doing our work.