I’d take this with a hefty pinch of thorium salts.

These guys are politicians first, scientists second - you don’t ascend to the head of their respective agencies without toeing the line, and being savvy to the political climate. The current political climate says nuclear bad, because it’s a safe position for re-election - no government wants to invest in nuclear power because the optics of nuclear disasters are terrible, and because the payback time is much longer than an election cycle.

The slow death of poor air quality (fossil fuels kill millions a year) and climate change are easy to wrangle politically, because you can treat them as externalities.