How far do you justify your subject in a biography?

I know next nothing about St Augustine, but I’m quite prepared to believe that his autobiography is “one of the great books of the world” (Lucy Beckett, TLS,  May 18 2016). But does writing a great autobiography mean that subsequent readers and biographers justify his every action? Here is Ms Beckett describing Augustine’s relations with women:

It’s sadder, and seriously unjust, that down the ages Augustine has taken much of the blame for the Church’s negative attitude to women and to sex. He lived faithfully with a poor Carthaginian woman for thirteen years, from when he was a seventeen-year-old student, and was devoted to their son. He was heart-broken when he had to send her back to Carthage from Italy because she couldn’t be fitted into the project (largely his mother’s) of a socially and financially beneficial marriage to underpin what was becoming his successful career. He replaced her briefly with another concubine before his final commitment to celibacy.

It's quite common for biographies to depict their subject in the best possible light; but on the basis of the above statement, it looks to me like Augustine has quite a lot to answer for the Church’s negative attitude to women. Heartbroken he may have been, and I’m sure I would be too, but he still left his wife and child for a career-enhancing marriage. Not quite the role model Ms Beckett would like Augustine to be.