The quote from Ng is

The big AI dreams of making machines that could someday evolve to do intelligent things like humans could, I was turned off by that. I didn’t really think that was feasible, when I first joined Stanford. It was seeing the evidence that a lot of human intelligence might be due to one learning algorithm that I thought maybe we could mimic the human brain and build intelligence that’s a bit more like the human brain and make rapid progress. That particular set of ideas has been around for a long time, but [AI expert and Numenta cofounder] Jeff Hawkins helped popularize it.

I think it's pretty clear that he would have worked on different things if not for Hawkins. He's done a lot of work in robotics, for example, so he could have continued working on robotics if he didn't get interested in general AI. Maybe he would have moved into deep learning later in his career, as it started to show big results.