You are the person who raised the issue of French airspace and thus ATC, not the carrier.

I suppose that you can just go ahead and file a claim. If it is paid, all the better. If not, you will at least have the carrier's reasoning as to why the delay was an extraordinary circumstance and you may elect to pursue it further or not.

The French airspace issue is a mess not just in French airspace but in adjoining areas because flights are pushed into those adjoining areas and the airspace becomes saturated.