I didn't want to take this at face value without context so I found when they discussed this. Check around 1:17:00 in this video.
https://youtu.be/lfBQoWxQaEM?si=6Ev6rx62KESH-HgR
And yeah, he did say exactly what the OP states. So... yeah.
To give the absolute benefit of the doubt, I could say they were referring specifically to nuclear fallout rather than the initial explosion, as a full on explosion is less likely in a nuclear plant emergency. But even assuming it was just an incredibly distasteful way to reference that, there are still thousands of deaths and even more injuries/illnesses associated principally with radiation poisoning.
This is not to say I'm against nuclear energy, but by god we've got to have more careful consideration than this.
Edit: As a bonus, Musk talks about his views on global warming around the 1:10 mark. The issue with greenhouse gasses is, uh... making it hard to breathe?
The "faith based therapy" thing make everything make a whole lot more sense...