I have only seen the "french only" statement applicable "in absence of ATC" or "in absence of AFIS" (i.e. Beauvais, Muret, Auch, Lasbordes...). In that case, since it becomes a non controlled airfield, how could they force you to use french (or even to use the radio at all!)
I undestand this as an advice, for you to know that probably there will be nobody speaking english at your arrival, but nothing more that that.
Last edited by Coolhand78; 18th Oct 2012 at 09:27.