Grace, mercy, kindness, and gentleness aren't always synonymous to "nice". English words often have deeper meaning, especially since the Bible covers complex depth when it comes to how we treat people. This episode is meant to show that being overly nice can be detrimental to someone's growth (and can be in fact a sin because you are refusing to tell the whole truth). Sure, I have been guilty of hiding the truth too, nobody is free from sin. My point is that we have to be able to admonish without sounding like Bible-bashing bigots.