I'm not a lawyer but that sounds ridiculous. If the french instructor was told that by the French authority it should be appealed. The French argue generally; how can you teach a French student the French syllabus if you cannot speak the language. However, as in the UK, you can be told nonsense at club level, spread widely by rumour. The french do not enjoy outside interference or compromise on their culture. Equally ridiculous. if true, is the reverse. To obtain a French issued licence, I've heard, then you must obtain a French English language assessment. This is required even if you are English born bred and hold a UK CAA English Language certificate at level 6. Then again I might be spreading a rumour as I haven't checked this officially.