Salaam ^Alaykum Khalil,
there has been a few important matters missed in this article,
When the Prophet spoke about gossip (ghibah), he gave a very specific definition. In a hadith related by Muslim, Abu Dawud, an-Nasa'iyy, and at-Tirmidhiyy, from the route of Abu Hurayrah, the Messenger, when asked about gossip (ghibah), said:
The Prophet defined gossip (ghibah) as mentioning something about your Muslim brother that he hates. The Prophet was asked, "What if that thing I mentioned was something truthful about him?" The Prophet said, "If it was in him, then you have committed gossip (ghibah), and if it was not in him, then you have committed al-buhtan"--which is a sin more enormous than gossip (ghibah).
There are certain cases the scholars of Islam excluded from being a sinful gossip (ghibah). These are classified into six categories, and one would not be sinful for committing gossip (ghibah) if his case fell into one of these six:
1. To go to the Muslim judge or one with jurisdiction to tell him about an injustice done to him in order to help him take his right.
2. To talk about a person’s sins that he hates mentioned, in order to seek help in preventing the person from continuing their sins. Hence, one is not sinful if he knows a Muslim who is committing a particular sin, and informs another of that matter so that the latter will help the sinful Muslim refrain from committing those sins.
However, be advised here of a very fine line: Many times a person lets loose his grudges against another to break him and seek revenge. Still, this person bluffs himself by claiming his intention is to help that person clear himself of his sin. In such a case, one does not escape the sin of gossip (ghibah).
3. To tell the mufti about someone else’s sin that he hates mentioned for the purpose of seeking the judgment of that particular matter. For example, for a man to tell the mufti his wife leaves the house against his permission does not make him sinful if one is seeking the religious judgment on that matter. However, the scholars said in such a case, one is recommended not to mention names, but to phrase the question in the third person. For example, to say: "What is the judgment according to the Religion if one's wife left the house against her husband’s permission?"
4. To depict a person with one of his attributes that he hates mentioned with the purpose of identifying him. For example, it is allowed for someone to tell his son to go and give some money to ‘the one-legged man next door,’ to clarify for the son exactly which man is meant.
5. To tell about another person’s sins which he himself openly declares. Hence, it is not sinful for one to tell about a person who himself declares he drinks alcohol or does so publicly.
6. To warn other Muslims against a sinner. This is a very important issue. It is an obligation on us to warn against those who cheat Muslims. If, for example, one knows of a waylayer targeting a route along which Muslims intend to travel, one would be sinful if he kept silent from warning the Muslims of this, thereby letting them fall prey to the waylayer. Moreover, it is more of an obligation to warn against those who cheat Muslims in their Religion than to warn against those who cheat in the worldly matters. If one knows of anyone who cheats the Muslims in their Religion, by falsely claiming to be knowledgeable, teaching them blasphemy, and/or giving them answers to Islamic questions that are incorrect--then it is an obligation to warn the Muslims against them.
At the time of our Master ^Umar Ibnul-Khattab, a man came to him and told him: "In the Era of Ignorance, I buried my daughter alive, however, at the last moment I took her out. Then Islam spread, and we became Muslims. Time passed, and then this daughter of mine fornicated and later attempted to commit suicide by slitting her wrists. Afterwards she repented a valid repentance. Some people asked me for her hand in marriage. I told them her story so that I would not cheat them about my daughter." ^Umar scolded that man and told him: "You have spread that which Allah ordered covered about your daughter. Let me warn you: If you tell anyone about this story again, I shall punish you in a manner that will make you an example for all the people."
From this story we understand that once a Muslim repents from his sins, it is unlawful to mention these sins about him. Therefore, the prevailing precept for the person must always be his prevailing situation.