most of the people who ended up aligning with that 
    movement did have good intentions. They were reasoning 
    that in the long term, nuclear power would bring great 
    misery to humanity. Long term thinking is good, right?

The problem is that those with good intentions didn't think very hard about the issue.

Even the occasional Fukushima or Chernobyl is preferable to the irreversible fossil fuel-induced hell we're about to experience, with potentially billions of people displaced and so forth. It's especially galling since protecting the planet was their entire raison d'etre.

And there were certainly who opposed nuclear power with evil intentions, specifically the fossil fuel industry.

I'm not sure which one is worse. At least the fossil fuel industry never claimed to be noble.