Could be a reference there to certain names which parents proposed being refused official recognition or registration on records in France simply because they were not on any official list that the government or Church would permit. This was rigidly enforced to the extent that at one time only names already on the list were accepted. It was relaxed later but parents cannot get any name recorded unless they can show that it falls within certain criteria; traditional, derived from a listed name, conventional within the parents' culture, not offensive and so on. In French 'to cry blue murder' is 'crier comme un putois' ( scream like a polecat ). Polecat as a name would hardly be accepted ! The name might just have sounded like 'murder' of course ; 'merde' (s**t) comes to mind as well as 'meutre' (murder) itself !