It was clarified later that the "hacker" was a security professional who put up all that data on the Dark Web to draw Zomato's attention to loopholes in its systems.
Edit - Turns out the OP's article mentions the same thing. Might as well confess a personal bias - every time I see a Daily Mail article, I can't help but think about how they served as a Nazi mouthpiece for years before the war, so all their stuff's got to be inaccurate/biased.
http://blog.zomato.com/post/160986258541/security-update-wha...
Edit - Turns out the OP's article mentions the same thing. Might as well confess a personal bias - every time I see a Daily Mail article, I can't help but think about how they served as a Nazi mouthpiece for years before the war, so all their stuff's got to be inaccurate/biased.