Amaral's reason for resigning was to cash in, since The PJ refused permission for him to publish why still being employed by that Institution. And at which point his salary ceased. So what did he think he was going to live on other than the proceeds of The Book? You could try telling me that.
His Honour had already been seriously damaged by then and wasn't going to be repaired by The Book.
This is what Amaral says in the foreword to his book.
‘Certainly, this book responds to the need I felt to defend myself, having been discredited by the institution for which I worked for more than twenty-six years, without being given any chance to explain myself, publicly or within the institution itself. I made the request several times, but it was never heard. I, therefore, scrupulously respected the rules of the police judiciaire and I refrained from making any comment. But this goes without saying: I experienced that silence to which I was constrained as an attack on my dignity. Later, I was removed from the investigation. It was then that I understood that it was time to speak. To do that, I requested early retirement in order to be able to express myself freely.’
We must take him at his word. Strangely not everyone is motivated by money and at that point he would have had his pension to live on.