Because being a hacker is about obsessively working to know all there is about a given subject and become better in a chosen craft. Bocuse was cooking hacker.
I forgot to mention - he was also a teacher of his craft and that counts too.
Because he was one of the most renowned chefs. Cooking can be quite nerdy, scientific and of course entrepreneurial. Modernist Cuisine is from a former Microsoft [1] guy, for example.