Occitan – what's left of it – is not actually particularly close to Parisian French, having more similarities with Catalan and (more distantly) the northern Italian languages; the idea that it's just a dialect or a set of dialects of the French language is propaganda for the same French cultural nationalism that lead to its OTL decline in the first place. The comparison with Spanish and Portuguese is actually pretty apt.
There's also the issue of "what do the people who matter in that TL consider these languages to be?". With the right POD, Portuguese could be considered a strange dialect or dialects of Spanish, whilst Austro-Bavarian could be considered distinct from German.