Given that the average Californian household uses around 7200kWh a year a single facility providing 9% of the state's energy needs or 2.89 million homes isn't that bad...
For a 1.2 billion dollars investment, that is about 415 dollars per household to keep it running for 5 years more.
Not saying that new nuclear generators are the best way since we have better alternatives, but you can't knock the benefits that nuclear energy has given us. If we were to reduce energy use by 10% today wouldn't we want to burn that much less natural gas and that little share of coal first if we cared about health impact? This buys us more time to have renewables displace the most harmful of generation methods.