Gas is dispatchable, nuclear is not. It’s enormously expensive, and that expense is locked in whether you need the power or not.

We’re already in a situation where we have more power than we need during certain hours of the day in some states/countries, and that’s not even counting the massive, accelerating buildout that will happen between now and the years before new nuclear is built… even it was started today.

Gas is used as backup in a grid dominated by cheap renewable. High capex sources like nuclear are a poor replacement.