It is illegal to promote ethnic hatred or deny the Holocaust in France, so...
(Related to the law you mentioned, in Germany they also have laws that are reactions to WWII, and they arrested some Chinese tourists for making Nazi salutes for tourist photos outside a government building last week.)
Treason is only possible if a country is at war (ie has an "enemy"). The speech would be protected as it is now (that wouldn't be the crime they break), but they could be found guilty of committing treason by the same (speech in this case) act.