if his reputation is low his new posts/comment will be not seen automatic by other users! i think its important moment.
I see nothing in source code to support this claim. There is a threshold under which the posts aren't shown, that's true, but to get it to that level it means literally eradicating that user from the platform. I don't see why I would do that, individually, instead of letting the community decide, collectively, by promoting what's considered valuable, instead of focusing on downvotting. If you focus on downvoting you set yourself up for low value, unconsciously.