France doesn't extradite its citizens, even absolute scumbags like Roman Polanski. Someone like Musk has lots of lawyers to gum up extradition proceedings, even if the US were inclined to go along. I doubt the US extradition treaty would cover this unless the French could prove deliberate sharing of CSAM by Musk personally, beyond reckless negligence. Then again, after the Epstein revelations, this is no longer so far-fetched.