David Shae is not credited for TWD on his page, I checked your reference but I could not find a credit whatsoever.
IMDb is not a reliable source for information. It is full of false info and other stuff that anyone can add in. The show The 100 is proof of that, as the IMDb pages tend to never match up to the actual casting for the show.
Hi, actually I follow TSDF which is a reliable source and David Shae has been spotted filming with the rest of the cast at jekyll island, follows several cast members, and is actually credited with a stunt double for 10x04 (same as Jerri Tubbs).