Before he was a food writer he worked in a number of fairly high-end restaurants in Boston (which he talks about occasionally on his Youtube channel), and then he opened his own restaurant in 2017ish. Not sure how that's "not a chef"
I simply didn't realize he had ever run a restaurant.
I feel like you have an overly restrictive definition of "chef". Owning a restaurant doesn't make you a chef, cooking food professionally does. Even if he never set foot in a restaurant kitchen, the man cooks food all day long for his job. That makes him a chef.
I have a chef's definition of a chef. You're welcome to use whatever one you prefer though.