The rules of French are not really legally defined; that’s a common misconception. Yeah, there is a state-funded cultural organization in France called the Académie française that claims that regulating the language is part of its mandate, but its “decisions” have no legal effect whatsoever and are widely ignored, even by the government and education system.
A prescriptivist will say that a term is “correct,” a descriptivist will say a term is “commonly accepted.”
Personally, this is what I say to prescriptivists: if they want a language with legally defined rules - they should learn French.