Think of a needle on a gauge representing public opinion about nuclear power. One half of the gauge reads green for nukes. The other half is red for no nukes.

If the needle is firmly in the green, a slight shift towards red in response to Fukushima might mean commissioning some studies and announcing a budget for upgrading the safety features.

But if the needle is just barely into the green, a slight shift moves it into the red and that means shutting them down. So yes, in a country where public opinion is divided, it is not out of the question to swing from yes to no in response to the biggest emergency since Chernobyl. I'm not sure about the phrase "knee-jerk," though. It may seem like a drastic move, like a leg kicking in response to a small tap, which implies a response out of [proportion to the stimulus.

However, perhaps the response is in proportion, it's just that when the needle is right on the dividing line, it only takes a small move to get from green to red?

Now that I write my thoughts out, I obviously agree with you :-)