it is simple, they feel like being Muslim they are becoming Arabicized or Asianized, and their loyalty to France would change that is why the new hatred against Muslims, in a diplomatic point of view you would not want French to become Muslims fearing retaliation, but that would not be Insaaf as all persons should have right to choose their own Deen ( path ). When I first heard that a lot of French man and woman becoming Muslims, I began to think okay now they are going to hate us, and soon look someone saying that, the Muslims are going to take over France and enslave humanity !!! I guess I can not blame them cuz that is the mentality they were born in, they think religion is only for show of cultural power !!! ALLAH TA-ALA give us all Hidayat.
PS : They do have a point cuz of the conquistador mind of some Turkish Sultan, who believed to bring peace in the world he would have to conquer the whole world and then teach them Islam !!! Shows how far had we gone out from fundamentals, there is no compulsion in Islam, If you think your path is the path to heaven you can not force others to your path of heaven and end up destroying your own chance of reaching heaven, but once you choose to be Muslim you should not be a hypocrite ( man I must perk up my Iman, I am so scared of everything but if I had a strong Iman I would only fear our Creator and the punishment for wrongdoing ), and so a lot of tribulations done to us we were to blame for it in a lot of ways, if we think we are Muslim then we must act as one.