Probably a misunderstanding. French press criticize the President 24/7. You can't insult the president or any other official in public, or any other French citizen.
Just like in most other European countries, France lets you say what you want, as long as you don't spread lies or hatred.
That makes sense, and I'll be the first to admit my understanding of French law was not as clear as it should have been, but the line between "criticise" and "insult" is very fine.
For instance, my understanding is that, in France, one should think twice before using the words "Mugabe" and "despot" in the same sentence. This is not a problem in the UK or the US at all.
But maybe this is also part of what made France such a very civilised, cultured and enjoyable place to live.
The line between criticize and insult is so fine, I can scarcely see it. It's like the line between the ocean and the beach.
Can a French person say "The president is illiterate.", as Americans have often said about their president? Could they say "The idiotic president keeps on making up words."? Harsh criticism is naturally insulting.
Insults are not (usually) hatred. It's closer to a rule against being rude, which doesn't seem to me like something that should be enforced by the police.
Just like in most other European countries, France lets you say what you want, as long as you don't spread lies or hatred.