Nagative feedbacks are *freedom of speech*???

Somone left me a nagative feedback and I have evidence that it is a gepletely lie. I called okay customer service, they told me that it is freedom of speech, buyers are allowed to lie as long as they do not use it to blackmail seller. I am a little confused. Okay, fine, I got a nagative feedback that is undeserving, I get it, things happen, I decided to move on, but to be told by a rep that people have the right to lie and lie is okay, that is something very odd indeed. The moral of okay is going downhill, I mean, I know it is more important to please buyers than sellers nowadays, but the good buyers do not lie, they are willing to hurt the good seller for bad buyers, makes me wonder if they need a management shake up.