I agree Krist's body of work is impressive, including many stunning images, but I also agree that the photos included with his ringing endorsement of Sony mirrorless are not great. They're not among his best photos. He also doesn't seem to tout the image quality--just praises the portability and versatility--of Sony mirrorless.
Sounds to me like he sees the switch as enabling him to more easily take photographs that before would have been difficult or impossible. Maybe in so far as he is concerned there isn't a question of image quality to be asked but rather does the camera get in his way to take photographs and it would appear that the answer to that question is "No."
As for why aren't any of his pictures "compelling" or "blowing you away" - if I was him, I wouldn't post my best on the Internet (either.) People will rip your material off without pause (including to use to make money with) on the Internet and I'm sure that anything he sees value in never comes close to a website before someone has paid him for it.