I would ask him this:
What was that thing which your mind was thinking when you struck with the idea of decentralised blockchain?
I’m interested in this because I really wonder how can one get the idea of blockchain out of nothing. There must be something, an incidence or event of life that motivated you to build something smart like this. Smart people always get motivation from real life events. We will probably never know but I’m sure a legend is going to be created for it, it is similar to the legend that Issac Newton understood gravity when an apple fell on his head, many says that anecdote is false and some others say it is true but it is irrelevant, the legend will keep on forever