Yes, IF he is trying to be really doing "the style," he's not that convincing. If he's having some fun playing the stuff, it's fun to hear him do that. That's how I view what I've heard.
As for Roberts, I've listened, do listen to a lot of the early giants too. And he sometimes on records gets close to really nailing it if you ask me. I've seen him four times live now, and he gets even closer live somehow. And he is one of the few pianists I've seen whose hands were literally a blur on some numbers. An impressive mofo!