No, Israel wanted to declare that they wouldnt be the first to use Nuclear weapons whilst at the same time not actually admitting to having them...If Israel said that they wouldnt be the first ones to use them , that would amount to admitting that they have them .
In 1968, they probably didn't have a nuclear weapon. But what's your basis for saying this? Is there some set of facts which you can point to support what you say? If there is, I'd be interested to know what those facts are. If there isn't, your explanation seems more than a little contrived. And it's hardly 'an official line'. So far, the evidence is a single secret document which is now comfortably middle aged - that's not usually what people mean when they talk about 'the official line'.