Ameen, then I wonder why we have 5 pages for this simple topic.
It seems to me that you're having difficulty understanding. Now pay attention,
Usman wasn't married to one of the Prophet's (pbuh) daughters, but in fact to two of them. This is a virtue towards privilege and an honour, not a merit towards superiority and highness.
Usman was a good man, in fact a very good man. This is why the Prophet (pbuh) married not one but two of his daughters to him. This is not a seal of approval to remain good for ever.
Usman was of a companion of the Prophet (pbuh) and a good man. This is not proof that he became a great Khalifa and got absolutely everything right and in order.
You are using his companionship, his relation to the Prophet (pbuh) as son in law and having the privilege to be married to two of the Prophte's (pbuh) daughters, as some kind of evidence to prove that he remained good and carried on to become a great Khalif, with no set backs and without getting anything wrong and out of control.
Gentlemen the man was a companion and son in law to the Prophet (pbuh), but this doesn't make him a saint or he didn't become a saint because of this privilege. Brothers, get use to reality and facts. You've been taught things which are not true, right from the very start and it's obvious you've become adapted to them.