Blogger Dr. Vino (a.k.a. Tyler Colman) is one of the most followed wine experts online. He's a certified authority as well, having published two books (Wine Politics and A Year of Wine), taught classes at New York University and the University of Chicago and completed a PhD dissertation examining the international wine economy. So yes, his use of the term "doctor" is legit.
Congratulations to Mei Lin, winner of Top Chef Season 12.