Absoultely right. We can abonish people for bad behaviors as long as we don't engage in them ourselves. The key to judging those is not to enforce God's law.
Jesus saved the prostitute because they were all guilty of some sort of sin. Based on God's law we all deserve to die.
When he said to her "sin no more" he was asking her to turn away from sin and turn herself toward God. Through Christ's grace she was "born again".
Jesus didn't "save a prostitute." Without going into the questionable history, seeing as how it was a later insertion absent from early copies of the Gospel according to John, the Pharisees brought Christ a woman accused of adultery and the narrative (not ethical guideline) is a story of a shameful situation in which they try to entrap Jesus so that they may have a charge to bring against him.