He's gonna be gone soon so he doesn't have much reason that he would be motivated to do anything. And there isn't a whole lot he can do, most French people - at least the ones in these cities - are pretty much on the side of the rioters here.
Le Pen is probably gonna get elected - by people who do not live in those cities - and she can send in the army to stop the rioting, but it's gonna be like Trump sending ICE into Chicago, the people in those cities will throw a tantrum over it.
For her, the move might make sense to project authority early in her presidency, for him in his lame-duck session it doesn't really make any sense, it can only potentially backfire and destroy his (already unimpressive) legacy.