So here is the situation: I look a 3 year postdoctoral position with a world famous chemistry professor who was in his late 70s at the time. During the 3 year period it seemed there was a real chance to send out novel work in a journal. However, at the end of the 3 year period my professor got unusually sick and started having breakdowns of sorts and has decided that since he doesn't like how the theoretical results look, he doesn't want them to be send out because it would not be presentable in a top journal and he only wants top journals. I am wondering if this means my ability to have a science career is doomed forever (this is my first postdoc after a PhD). I mean, at the time he had a solid track record of producing publishable work and it seemed the work he was doing had the potential to lead to novel results and I was not anticipating he'd break down this way/ What does this mean for me?

Have you explained to him that you have spent three years on it and that you need to publish or perish? He might be more susceptible to emotional arguments in this break down state.

Is he correct or not about the quality of the theoretical results?

Yes, what is your take on the results? If you're happy with them, you could be sole author. Or else get someone else on board, take their feedback, and co-author with them?