How is that relevant in this context, though? Why is it bad faith when we're talking about grid-supplied electricity generation? We need electricity generation, and most of France's is nuclear. It seems uncontroversial.
It's because the "if it hasn't been done, it can't be done" argument applies to nuclear displacing fossil fuels. Remember, the decarbonization goal has to be all uses of fossil fuels, not just their use for the grid.