Last I saw he was still using the same basic putt but he's been practicing it for 2+ years now and it looks a lot smoother, both in delivery and the flight of the disc. There's no ****ty wobble anymore.
Putting may not be the strongest part of his game but that's only because he can throw so damn far. Most people would still be amazed at how good his putting is. He can throw a putt freaking hard with that short arm method and it's difficult to see where the power is coming from. That method does help learn good timing with your weight shift and the palm push because it all happens in such a short window of time. I used it for a while but switched to a slower, smoother push putt because I had significant blow by problems with the short arm method.