Although I was still only at primary school when the nuclear shit hit the fan in NZ, I think I would be correct in saying that the attitudes then were the same. I think (I hope) we are going to go the other way on GE - that is, continue to allow GE research. For better or for worse, we went the nuclear-free way in the 80s. That we could now reverse that I very much doubt. Apart from the huge amount of international back-tracking the government would have to do, no government that reversed the nuclear-free policy could possibly survive the following election.
Abolishing "nuclear-free" would be akin to abolishing the all blacks, or coming up with a programme to declare kiwis pests and eradicate them. It has become part of the national identity and I think that the world for the most part has come to accept it, as one of NZ's quirks and as part of our "clean green" tourism image. I take your point about rupture though.
As for the relevance of the Nuke free debate; I agree it's not likely to change now. It's not even very important whether it does. That was a policy based on a war that's over now. In the next war, other policies are going to be more important.
However, I think the ideas and attitudes behind the decision ARE still relevant. As you say, it seems to be echoing back in this debate over GE foods. If the attitudes and assumptions are wrong, they will continue to poison the debate over everything for decades to come. If they are right, then the way the apply to modern problems needs to be established.
Some people might see it as just rehashing old cold-war arguments. I see it as a continuing search for truth.