This is absurd in several levels - you can't move electricity in a box, there are only a few interconnects, all of them regulatable and controllable, they can only move like 15% of tital supply and prices are different for business and for home use.

And nothing you've said seems to have relevance to shortages

Yes exactly, your chosen option is to disconnect France from the shared grid (calling it "regulation" doesn't change anything).

There are already electricity price controls in France, which still also exports at market prices.

As ClumsyPiloy said electricity is not something you can easily trade under the radar of the regulator. Technical limitations and regulation do change everything.