what these people did, or their motive for doing it, I think there's a case to be made for a legal process that enables money to be extracted from child abusers by way of compensation. It might be placed in some form of trust account for the benefit of the child concerned, and spent at the discretion of trustees - who wouldn't necessarily be the parents.
My reason for taking that view is that I know there are cases where abusers go to court, plead guilty, and are released back into the community after serving a minimal sentence. It doesn't seem fair to a traumatised child that such a small price is often paid by its abuser, whereas a steep financial penalty would benefit the victim and penalise the perpetrator.
the parents are guilty of living off immoral earnings."
Whilst I can sympathise with the sentiment behind that comment it's not the case - the parents are guilty of no such thing. They might have been guilty of blackmail if the culprit hadn't paid up so willingly, but he readily complied with their request, and in truth I doubt there's any charge that can be brought against them in a legal sense, although they're obviously devoid of any sort of moral values.