In the context Jesus says to Levi the tax collector: 'Follow me'. And Levi did, which means I think he repented and became righteous.
The pharisees and scribes were criticizing Jesus (for eating with tax collectors and sinners,) which means they didn't repent. So they were not the righteous ones Jesus talked about. Jesus was and is the one who has the power to forgive sins and he is our one Mediator. Luke 5:24 But so that you can be sure that the Son of Man does have the authority on earth to forgive sins…” he said to the paralyzed man, “I am telling you, get up, pick up your mat, and go home.”