Russo also wrote a book that revealed very private details of his late mother's life. Did he owe her still-living friends and relatives silence until they too were gone? The conclusion is: no, authors write about what seizes their attention. But he doesn't really seek to absolve himself. It's more like an addict talking about addiction: "I took another drink, because that's the compulsion I felt."
The well-received story about a Belgian nun was received mostly among his English-language readers in the United States. Not nuns or Belgians. What was the Belgian nun reception like? Russo doesn't know. He suspects it would be less enthusiastic, because they would spot the cracks in his story more readily. The closer the readers are to the life experience of the characters, and the further the author is from his characters, the more the author risks readers' trust in trying to write those characters.
There's also a characterization-gap risk regarding authors and other authors as well as regarding authors and readers. If Russo sells novels with characterizations of Belgian nuns or black men, what does that do to the literary prospects of actual Belgian nuns or black men who are trying to sell their first manuscript? Can he end up non-maliciously but thoroughly quashing their publishability just by showing up first, even if his nuns are less authentic than those written by an actual nun? Quite possibly, yes. Russo posits that the struggle for position among authors has become more desperate in recent years. Publishers aren't as patient about investing in new talent because they are facing more financial pressure. That means that established authors like himself can casually, even accidentally, displace authors who could draw better portraits of certain kinds of characters. That's unfortunate for those would-be authors and for the reading public.