Research has found you cannot control nuclear proliferation with half measures.

If you allow nuclear work, there will be accidents and fake "accidents." It will get increasingly difficult to keep nuclear weapons impossible to make at scale for random jihadists, and that's maybe not even as big of a problem as constantly increasing accidents.

Right now the "orphan source" category of accidents already happens way too many times a year. That's where nuclear material ends up "lost" in unknown locations, just out in the world somewhere, and people get killed by randomly finding these sometimes (so far mainly in eastern Europe, but let's not make it worldwide).

Also, fundamentally, nuclear power is just a way to get energy, not a way to balance energy needs. As long as we have a mindset of "consume as much energy as we can as fast as we can and see what kind of record setting mass extinction we can die in," it's inherently not really helpful to have another way to consume energy fast. A billion gigawatt hours generated with nuclear energy don't actually save a billion gigawatt hours from being generated with coal unless you're actually smart enough to limit your energy use. And if you're smart enough to do that, you might as well limit it to pretty much what you can get with the safest possible renewables, not nuclear