My guess is that they want to be the ones who ration power. They get to be the ones to pick winners and losers. And the people running the plants will be political appointees who know nothing about running a Nuclear Power Plant. Maintenance will not be funded and the plants will fall into disrepair.
The power will go to the corporations that make the largest campaign contributions.
Given the track record of nationalization better get your Belgian Chocolates and your Brussel Sprouts while they’re not hot!