I have been liaising with Stern parts dept. They plan to make more but they are waiting on materials from vendors and are not currently available and have no ETA on when they will be. I let them know that there were multiple folks who needed them. I also called Marco who said they are showing as No Longer Available by Stern but have a back order for them. So keep checking Marco. Kinda stinks as this is a custom part and nowhere else you can get it.
Note that Marco did get more "Groot Jaw Assemblies" in, which based on the online description include the jaw piece itself. Even though $89 and more parts than I needed I went ahead and ordered it because it was supposed to come with the jaw piece. It came, but without the jaw piece, and Marco promptly and kindly issued a refund. So, I don't recommend buying that assembly if you are looking only for the jaw piece.