Interesting thread...
I have a question. All the airports/aerodromes in France which request 'FR-seulment', at least all that I've seen, are uncontrolled airports. Then, if a pilot is not even required to use the radio on uncontrolled airspace, how can he be forced to use french?
Couldn't it be acceptable to enter in one of those aerodromes without making radio calls at all?