Modern frequencies for France normally aren't all that helpful, I'm afraid. There are lots and lots of North Africans in southeastern France as well as in other parts of France. It can total 20% or more of the population. You should visit Marseilles.
I'd be very surprised if the study from which the pie chart comes used only men with French last names. Could you direct me to the page in the study where it says that? It seems a bit unlikely given how French law prohibits "racial" or ethnic identification in most matters.
We also shouldn't forget Fraxinetum, and it's possible effect not only on Provence, but neighboring areas. I think the Auvergne could be explained that way through a spread from there and then some founder effect if it's really found in men with French surnames. After all, Nimes, where three Berber skeletons of the Medieval period were buried facing Mecca, is not all that far from some parts of the Auvergne.
https://en.wikipedia.org/wiki/Fraxinetum
It seems that some percentage of the pirates were actually Muslim converts from Andalucia, which might be another reason for some Iberian specific R1b in that area and even western Liguria.
Of course, given the small number of men, their autosomal signature would have been wiped out pretty quickly.
Unless the yDna analysis got down very far into subclades to determine if these are men with parentage from North Africa recently or from the Middle Ages, I would think.