“It was kind of like a religious conversion. Being anti-nuclear was an essential part of being an environmentalist for a long time but now that I’m talking to a number of environmentalists about this, it’s actually quite widespread this view that nuclear power is not ideal but it’s better than climate change.”That 'religious conversion' point is particularly telling. Steven Landsburg argued years ago that environmentalism was never about saving the environment, it was about following the cathecism.
Things which 'sound' wrong have always been opposed by environmentalists whether they would be a good thing or not - look at Tindale's 'Being anti-nuclear was an essential part of being an environmentalist'. This is certainly something that happens in other areas - I remember when I was a member of an anti-war group in Birmingham, it was widely accepted that in order to oppose the Iraq war you had to oppose the Israeli occupation (I had no problem with that, but why the two should be inherently linked, I have no idea), and it's both irrational and damaging to the cause.
Landsburg's classic example of a basic tenet of enviornmentalistm that may or may not have anything to do with the good of the environment is recycing paper. There is at least a possibility that recycling paper reduces the total number of trees on the planet, by making owning trees less profitable - this may or may not be true, but how many environmentalists would even bother to entertain the notion. Recyling is a Good Thing, wasting paper is a Bad Thing - and you will be shunned for suggesting otherwise (seriously - try it with one of your green friends some time).
Conformity bias is a powerful force, as is consistency bias - the fact that four powerful figures have changed their minds about such a major issue is surely an encouraging sign for environmentalism - whether or not nuclear power is a good thing (I'm pretty convinced it is, but that's not the issue), it's good that environmentalists are willing to actually look at the facts, maybe one day they'll even give their backing to GM....