I'm guessing, given the publisher's (Tyson Cornell) history and the scope of the books available, they probably aren't taking queries as much as they are doing books they've heard about and are passionate about coming through the word-of-mouth of their existing network of author friends and cultural mavens. Tyson worked with many literary heavyweights when he was at Book Soup and the biographies of the authors he's working with are pretty distinguished. I think this will be another company that doesn't have submission guidelines because it isn't actively "looking."