You make a good point.
With France's military estimated to be between 15-20% Muslim, a conventional attack against a Muslim country is problematical. Just imagine the scale of fragging, sabotage and mutiny which would take place in the ranks! In fact, using the army inside France against Muslims would be problematical.
However, using nuclear weapons involves a lot less of the military and is more likely to involve those who are actually loyal to France.
Using nuclear weapons may be their only option. France has nearly been moved into checkmate by her Muslim hordes.
We in Britain have a regiment whose speciality is killing Muslims - they are called The Ghurkas!
The Ghurkas then:
http://www.himalayan-imports.com/faq/Ghurkas.htm
and The Ghurkas now:
http://www.army.mod.uk/brigade_of_gurkhas/rgr/index.htm