Note that not only the Duke of Anjou renounced his rights on the throne of France, for himself and for his descendants. Also his brother the Duke of Berry and his uncle the Duke of Orléans (direct benefactors of this renunciation) on their turn renounced their rights on the throne of Spain, for themselves and for their descendants. Finally King Louis XIV issued a Letters Patent assenting these three renunciations.
These reciprocal renunciations to the throne of France (by Anjou) and to the throne of Spain (by Berry and Orléans), sealed by King Louis XIV were intended to settle the balance of power in Europe on a permanent basis by permanently separating the French and Spanish Crowns. That these acts were reciprocal made them dependent upon each other, so that the breach of the terms by one party would thereby invalidate the obligations made by the other party.
The Légitimists, the supporters of Don Luis Alfonso, do act like it was all a misunderstanding by a French Prince (Philippe, Duc d'Anjou), that it was illegal and that therefore their "candidate" is the rightful Heir to the throne of France. But it is clear that all this was deliberately and extensively negotiated, involved the King himself (Louis XIV) and three Princes of the Blood Royal (Philippe Duc d'Anjou, Charles Duc de Berry and Philippe Duc d'Orléans) and sealed off by all the great powers of the time.