The French have never had to learn the lesson we Americans call "blowback."
We supported the mujahedin in Afghanistan... and twenty years later they attacked us. We support Iraq in the Iran-Iraq war, even going so far as to look the other way as they both developed and used weapons we had committed to destroying, and twenty years later we fought a war to deprive them of those weapons.
If the French give (say) Syria nuclear weapons, how many decades will it be before a Syrian nuclear weapon explodes on French soil?
Giving the enemies of Israel nuclear weapons is not only immoral, it's profoundly stupid.